SC 13D/A

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934
(Amendment No. 13 )*

OPTICAL SENSORS INCORPORATED

(Name of Issuer)

Common Stock $.01 par value per share

(Title of Class of Securities)

68384P107

(CUSIP Number)

Hayden R. Fleming
17797 N. Perimeter Drive, Suite 105
Scottsdale, AZ 85255
(480) 419-7811

(Name, Address and Telephone Number of Person Authorized to
Receive Notices and Communications)

March 15, 2006

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. o

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

CUSIP No. 68384P107  Page 2  of  10 

1	NAMES OF REPORTING PERSONS: HAYDEN R. FLEMING
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ
	(b)   o
3	SEC USE ONLY:
4	SOURCE OF FUNDS (SEE INSTRUCTIONS):
	AF AND PF
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):
	o
6	CITIZENSHIP OR PLACE OF ORGANIZATION:
	U.S.A.
		7	SOLE VOTING POWER:
NUMBER OF			6,151,694
SHARES		8	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			662,843
EACH		9	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			6,151,694
WITH		10	SHARED DISPOSITIVE POWER:
			662,843
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	6,814,537
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):
	74.6%
14	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	IN

CUSIP No. 68384P107  Page 3  of  10 

1	NAMES OF REPORTING PERSONS: CIRCLE F. VENTURES, LLC
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	86-0820669
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ
	(b)   o
3	SEC USE ONLY:
4	SOURCE OF FUNDS (SEE INSTRUCTIONS):
	WC
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):
	o
6	CITIZENSHIP OR PLACE OF ORGANIZATION:
	Georgia - U.S.A.
		7	SOLE VOTING POWER:
NUMBER OF			2,552,828
SHARES		8	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			NONE
EACH		9	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			2,552,828
WITH		10	SHARED DISPOSITIVE POWER:
			NONE
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	2,552,828
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):
	27.9%
14	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	OO

CUSIP No. 68384P107  Page 4  of  10 

1	NAMES OF REPORTING PERSONS: CIRCLE F. VENTURES II, LLC
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	46-0476684
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ
	(b)   o
3	SEC USE ONLY:
4	SOURCE OF FUNDS (SEE INSTRUCTIONS):
	WC
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):
	o
6	CITIZENSHIP OR PLACE OF ORGANIZATION:
	Arizona - U.S.A.
		7	SOLE VOTING POWER:
NUMBER OF			3,179,885
SHARES		8	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			NONE
EACH		9	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			3,179,885
WITH		10	SHARED DISPOSITIVE POWER:
			NONE
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	3,179,885
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):
	34.8%
14	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	OO

CUSIP No. 68384P107  Page 5  of  10 

1	NAMES OF REPORTING PERSONS: Hayden R. Fleming and LaDonna M. Fleming Revocable Trust
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ
	(b)   o
3	SEC USE ONLY:
4	SOURCE OF FUNDS (SEE INSTRUCTIONS):
	PF
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):
	o
6	CITIZENSHIP OR PLACE OF ORGANIZATION:
	ARIZONA - U.S.A.
		7	SOLE VOTING POWER:
NUMBER OF			NONE
SHARES		8	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			662,843
EACH		9	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			NONE
WITH		10	SHARED DISPOSITIVE POWER:
			662,843
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	662,843
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):
	7.0%
14	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	OO

CUSIP No. 68384P107  Page 6  of  10 

1	NAMES OF REPORTING PERSONS: FLEMING SECURITIES INC.
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	85-0416641
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ
	(b)   o
3	SEC USE ONLY:
4	SOURCE OF FUNDS (SEE INSTRUCTIONS):
	OO
5	CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e):
	o
6	CITIZENSHIP OR PLACE OF ORGANIZATION:
	NEW MEXICO - U.S.A.
		7	SOLE VOTING POWER:
NUMBER OF			415,648
SHARES		8	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			NONE
EACH		9	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			415,648
WITH		10	SHARED DISPOSITIVE POWER:
			NONE
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	415,648
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11):
	4.5%
14	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	OO

SCHEDULE 13D/A

Item 1. The title of the class of equity securities to which this statement relates is Common Stock, par value $.01 per share (the “Common Stock”). The name of the issuer is Optical Sensors Incorporated (the “Company”). The principal executive office of the Company is 7615 Golden Triangle Drive, Suite C, Eden Prairie, MN 55344.

Item 2. Identity and Background

     The reporting persons are Hayden R. Fleming, Circle F Ventures, LLC (“Circle F”), Circle F Ventures II, LLC (“Circle F II”), the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust (the “Fleming Trust”) and Fleming Securities, Inc. (Fleming Securities). Hayden R. Fleming is the managing member of Circle F and Circle F II, a Trustee of the Fleming Trust and President and principal shareholder of Fleming Securities. Circle F is a Georgia limited liability company and Circle F II is an Arizona limited liability company. Fleming Securities, Inc. is a New Mexico Corporation. The principal business of Circle F and Circle F II is the operation of a private investment fund. Fleming Securities is a registered broker dealer. The principal business and office of both Circle F and Circle F II and of Fleming Securities and the Fleming Trust is located at 17797 N. Perimeter Drive, Suite 105, Scottsdale, Arizona 85255. Hayden R. Fleming, Circle F, Circle F II, Fleming Securities and the Fleming Trust have not been parties to any civil or criminal proceeding required to be disclosed in response to this Item.

     The following information is provided for Hayden R. Fleming:

(a)	Name. Hayden R. Fleming.
(b)	Address. 17797 N. Perimeter Drive, Suite 105, Scottsdale, Arizona 85255.
(c)	Principal Occupation and Employment. Hayden R. Fleming is the principal of Fleming Securities, Inc., a broker/dealer.
(d)	Criminal Proceedings. None.
(e)	Civil proceedings. None.
(f)	Citizenship. United States of America.

Item 3. Source and Amount at Funds or Other considerations.

     Personal funds of Hayden R. Fleming and the Fleming Trust. Working capital of Circle F and Circle F II. Services of Fleming Securities.

Item 4. Purpose of Transaction

     All of the reported shares are held for investment purposes.

     The Company does not presently intend to sell additional shares of Series C Convertible Preferred Stock directly to investors with the assistance of Fleming Securities, Inc., as agent. However, the Company may issue additional shares of Series C Convertible Preferred Stock upon conversion of a series of convertible promissory notes currently being sold by the Company totaling up to $4,500,000 in principal amount. On the sale of any such convertible promissory notes, Fleming Securities, Inc. is entitled to receive a warrant to purchase Common Stock at a price of $2.70 per Common share in an amount equal to 10% of the as converted number of shares of Common Stock issuable upon conversion of any such shares of Series C Convertible Preferred Stock so issued. Currently, there are 64,962 shares of Series C Convertible Preferred Stock authorized and available for issuance by the Company.

Page -7-

     The reporting persons have no other plans or proposals that relate to or would result in:

(a)	The acquisition by any person of additional securities of the Company, or the disposition of securities of the Company except as provided in Item 5(c) below.
(b)	An extraordinary corporation transaction, such as a merger, organization or liquidation, involving the Company or any of its subsidiaries;
(c)	A sale or transfer of a material amount of assets of the Company or any of its subsidiaries;
(d)	Any change in the present board of directors or management of the Company, including any plans or proposals to change the number or term of directors or to fill any existing vacancies on the Board;
(e)	Any material change in the present capitalization or dividend policy of the Company;
(f)	Any other material change in the Company’s business or corporate structure;
(g)	Changes in the Company’s charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Company by any person;
(h)	Causing a class of securities of the Company to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association;
(i)	A class of equity securities of the Company becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Act; or
(j)	Any action similar to any of those enumerated above.

Item 5. Interest in Securities of the Issuer

     (a) Number of Shares/Percentage of Class Beneficially Owned.

     (i) Circle F beneficially owns 2,552,828 shares of the Company’s Common Stock representing 27.9% of the outstanding shares of Common Stock. Of such shares, 1,259,328 shares and warrants to purchase 83,333 shares are owned directly by Circle F. The balance of such ownership arises on an as converted basis from Circle F’s holdings of 4,333,333 shares of Series A Convertible Preferred Stock that are convertible into 722,222 shares of Common Stock, 56,333 shares of Series B Convertible Preferred Stock which are convertible into 281,665 shares of Common Stock and 5,157 shares of Series C Convertible Preferred Stock which are convertible into 206,280 shares of Common Stock. See Recent Transactions below.

     (ii) Circle F II beneficially owns 3,179,885 shares of the Company’s Common Stock representing 34.8% of the outstanding shares of Common Stock. All of such ownership arises on an as converted basis from Circle F II’s holdings of 180,601 shares of Series B Convertible Preferred Stock which are convertible into 903,005 shares of Common Stock and 56,922 shares of Series C Convertible Preferred Stock which are convertible into 2,276,880 shares of Common Stock. See Recent Transactions below.

Page -8-

     (iii) The Hayden R. Fleming and LaDonna M. Fleming Revocable Trust (the “Trust”) owns 639,431 shares of the Company’s Common Stock representing 7.0% of the outstanding shares of Common Stock. The Trust owns 211,814 shares of the Company’s common stock. A portion of the Trust’s ownership arises on an as converted basis from the Trust’s holdings of 8,496 shares of Series C Convertible Preferred Stock which are convertible into 339,840 shares of Common Stock. The Trust holds a $100,000 convertible promissory note that is convertible into 1,111 shares of Series C Convertible Preferred Stock, which in turn are convertible into 44,444 shares of Common Stock. Warrants to purchase 43,333 shares of Common Stock are included in the number of shares owned by the Trust. See Recent Transactions below.

     (iv) Fleming Securities owns 415,648 shares of the Company’s Common Stock representing 4.5% of the outstanding shares of Common Stock. All of such shares arise from warrants to purchase 415,648 shares of Common Stock. See Recent Transactions below.

     (v) Hayden R. Fleming beneficially owns 6,814,537 shares of the Company’s Common Stock representing 74.6% of the outstanding shares of Common Stock. Of such shares, 2,552,828 shares are owned by Circle F, 3,179,885 shares are owned by Circle F II, 23,412 shares are owned by an individual retirement account for the benefit of Hayden Fleming’s wife, 3,333 shares are owned by an individual retirement account for the benefit of Hayden Fleming, 639,431 shares are owned by the Trust for the benefit of Hayden Fleming and his wife and 415,648 are owned by Fleming Securities, Inc. See Recent Transactions below.

     (b) Nature of Ownership. Circle F has sole power to vote and direct the disposition of all 2,552,828 shares reported as owned by it. Circle F II has sole power to vote and direct the disposition of all 3,179,885 shares reported as owned by it. Fleming Securities has sole power to vote and direct the disposition of all 415,648 shares reported as owned by it. Hayden R. Fleming has sole power to vote and direct the disposition of 6,151,694 of the reported shares and has shared power to vote and direct the disposition of 662,843 of the reported shares that are owned jointly with his wife in the trust or for the benefit of his wife.

Recent Transactions: Pursuant to a Stock Purchase Agreement dated May 6, 2005, Circle F, Circle F II and the Trust, collectively, purchased a total of 66,686 shares of Series C Preferred Stock at a price of $90 per share for an aggregate purchase price of $6,001,849.31. Each share of Series C Preferred stock is convertible into forty (40) shares of Common Stock at a conversion price of $2.25 per Common shares. Of the Series C Preferred Stock purchased, Circle F converted prior advances to the Company, interest and expenses totaling $464,178.08 into 5,157 shares of Series C Preferred Stock that are convertible into 206,280 shares of Common Stock. Circle F II converted prior advances to the Company and expenses totaling $5,123,000 into 56,922 shares of Series C Preferred Stock that are convertible into 2,276,880 shares of Common Stock. The Trust converted prior advances to the Company and interest totaling $414,671.23 into 4,607 shares of Series C Preferred Stock that are convertible into 184,280 shares of Common Stock. As agent for these transactions and additional financing of $750,000, Fleming Securities, Inc. received a warrant to purchase 300,084 shares of Common Stock at an exercise price of $2.70 per common share.

Pursuant to a Joinder Agreement dated March 15, 2006, the Trust converted prior advances to the Company totaling $350,000 into 3889 shares of Series C Preferred Stock that are convertible into 155,560 shares of Common Stock. As agent for this transaction, Fleming Securities, Inc. received a warrant to purchase 15,556 shares of Common Stock at an exercise price of $2.70 per common share.

Pursuant to a Note and Warrant Purchase Agreement dated March 15, 2006, the trust purchased a

Page -9-

Convertible Promissory Note in the amount of One Hundred Thousand dollars ($100,000) with a detachable 5-year warrant to purchase Ten Thousand (10,000) shares of the Company’s Common Stock at an initial exercise price of $2.25 per share. The Note is convertible into 1,111 shares of the Company’s Series C preferred stock at a price of $90 per share. Those Series C shares, in turn, are convertible into 44,444 shares of Common Stock. As agent for this transaction, Fleming Securities, Inc. received a warrant to purchase 4,444 shares of Common Stock at an exercise price of $2.70 per common share.

In addition, Fleming Securities acted as agent for the Company with respect to a series of other joinder agreements to the Stock Purchase Agreement dated May 6, 2005 that sold 23,891 additional shares of Series C Convertible Preferred Stock to accredited investors. For such services, Fleming received or is entitled to receive warrants to purchase 95,564 shares of Common Stock at an exercise price of $2.70 per common share.

     (c) Rights to Dividends or Proceeds. None.

     (d) Not Applicable

Item 6. Contracts, Arrangements, understandings or Relationships With Respect to Securities of Issuer.

Under the Stock Purchase Agreement dated May 6,2005, upon written request by the holders of at least an aggregate of 40% of the outstanding Series C Convertible Preferred Stock, the Company agreed to use its reasonable best efforts to cause a registration statement to be filed and remain effective until the earlier of (1) the sale of all the shares of the Company’s common stock covered by the registration statement; or (2) such time as the selling stockholders named in the registration statement become eligible to resell the shares of the Company’s common stock pursuant to Rule 144(k) under the Securities Act of 1933.

Except as described herein, and as described under Item 4, there are no other contracts, arrangements, understandings or relationships between Circle F, Circle F II, the Trust and any other person with respect to any securities of the Company.

Item 7. Materials to be Filed as Exhibits.

Exhibit 1	Joinder Agreement, dated March 15, 2006, by and between the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust and Optical Sensors Incorporated.	Filed herewith electronically.
Exhibit 2	Note and Warrant Purchase Agreement dated March 15, 2006 between the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust and Optical Sensors Incorporated.	Filed herewith electronically.

Page -10-

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: March 17, 2006	/s/ Hayden R. Fleming
	Hayden R. Fleming
	Name/Title
Date: March 17, 2006	Circle F Ventures, LLC
	By /s/ Hayden R. Fleming
	Name/Title: Hayden R. Fleming —
	Managing Member
Date: March 17, 2006	Circle F Ventures II, LLC
	By /s/ Hayden R. Fleming
	Name/Title: Hayden R. Fleming —
	Managing Member
Date: March 17, 2006	Hayden R. Fleming and LaDonna M. Fleming Revocable Trust
	By /s/ Hayden R. Fleming
	Name/Title: Hayden R. Fleming —
	Trustee
Date: March 17, 2006	Fleming Securities, Inc.
	By /s/ Hayden R. Fleming
	Name/Title: Hayden R. Fleming —
	President

EX-1

Exhibit 1

JOINDER AGREEMENT
TO
STOCK PURCHASE AGREEMENT

     Optical Sensors Incorporated, a Delaware corporation d/b/a väsamed, with its principal place of business at 7615 Golden Triangle Drive, Suite C, Eden Prairie, Minnesota 55344 (the “Company”), and Circle F Ventures, LLC, Circle F Ventures II, LLC and the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust (the “Circle F Investors”) and Barth Investment Company II, L.P. (the “Investor”) (the Circle F Investors and Investor, collectively, the “Series C Investors”) executed a Stock Purchase Agreement (“Stock Purchase Agreement”) effective as of May 6, 2005.

     Under the Stock Purchase Agreement, the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust (the “Fleming Trust”) purchased 4,607 shares of the Company’s Series C Preferred Stock (as such term is defined in the Stock Purchase Agreement). Thereafter, on July 15 and July 22, 2005, the Fleming Trust made advances totaling $350,000 to the Company (the “Advances”). Through conversion of such Advances, the Fleming Trust now desires to purchase 3,889 additional shares of the Company’s Series C Preferred Stock as set forth on Schedule A-1 attached hereto, at a purchase price of $90.00 per share pursuant to the terms of the Stock Purchase Agreement and thereby add to its share position as a party to the Stock Purchase Agreement. The Company desires to issue 3,889 shares of the Company’s Series C Preferred Stock in conversion of the Advances made by the Fleming Trust.

     The Company also desires to qualify its representations and warranties contained in Section 4 of the Stock Purchase Agreement pursuant to the Schedule of Exceptions attached hereto as Schedule B-1 and hereby makes such representations and warranties as of the date hereof for the benefit of the Fleming Trust.

     Fleming Trust hereby agrees to convert the Advances into the number of shares of the Company’s Series C Preferred Stock set forth on Schedule A-1 at a purchase price of $90.00 per share pursuant to the terms of the Stock Purchase Agreement. Fleming Trust agrees that upon conversion of the Advances any indebtedness represented thereby, including interest thereon, if any, shall be discharged and paid in full. Fleming Trust hereby explicitly affirms and acknowledges the representations and warranties set forth in Section 5 of the Stock Purchase Agreement.

     IN WITNESS WHEREOF, the Fleming Trust and the Company have executed this Joinder Agreement effective as of March ___, 2006.

HAYDEN R. FLEMING AND LADONNA M. FLEMING REVOCABLE TRUST		OPTICAL SENSORS INCORPORATED
By	/s/ Hayden R. Fleming	By	/s/ Paulita LaPlante
Hayden R. Fleming, Trustee		Paulita LaPlante, President and CEO

SCHEDULE A-1

Name of Investor	Date of Investment	Amount of Advances		Number of Shares
Hayden R. Fleming and LaDonna M. Fleming Revocable Trust	March 15, 2006	$	350,000		3,889
17797 N. Perimeter Drive, Suite 105
Scottsdale, AZ 85255
Totals:		$	350,000		3,889

SCHEDULE B-1

SCHEDULE OF EXCEPTIONS

     This Schedule of Exceptions is being delivered pursuant to the Stock Purchase Agreement dated May 6, 2005 (the “Purchase Agreement”). Capitalized terms not defined herein are used as defined in the Purchase Agreement. Section references are applicable to the sections of the Purchase Agreement. Any item disclosed in any section of this Schedule of Exceptions is deemed disclosed with respect to the applicable section of the Purchase Agreement and all other sections of the Purchase Agreement for which the same is fairly disclosed.

Section 4(f) — Financial Statements. The Company has no material liabilities, known or unknown, absolute, contingent or otherwise except for:

Liabilities that are set forth in the Financial Statements, the notes thereto or the SEC Reports.

Liabilities that have been incurred in the ordinary course of business since September 30, 2005.

Section 4(g) — No Material Adverse Change. There have not been any changes in the assets, properties, liabilities, financial condition, business or operations of the Company from that reflected in the Financial Statements except for:

Changes in the ordinary course of business which have not been, either individually or in the aggregate, materially adverse.

The Company’s continued operating losses and negative cash flow.

On January 27, 2006, the Company filed a Certificate of Increase of Shares of Series C Preferred Stock with the Secretary of State of Delaware for the Company’s Series C Stock that increased the number of authorized shares of Series C Stock from 115,000 to 166,666.

On February 6, 2006, the Company commenced a bridge financing, pursuant to which the Company plans to issue in a private placement convertible promissory notes in the aggregate principal amount of up to $4,500,000 (the “Notes”) with detachable warrants. The Notes bear interest at the rate of ten percent per annum until paid in full. All outstanding principal and interest on the Notes is due and payable eighteen months from the date of issuance unless converted pursuant to the Notes terms prior to such date. The Notes will be secured by a security interest in all of the Company’s assets, except for the Company’s intellectual property.

The Notes are convertible, at the option of the holders, into shares of the Company’s Series C Preferred stock (“Series C Stock”) at a conversion price of $90.00 per share (the “Conversion Price”). All outstanding principal and, at the Company’s election, accrued interest under the Notes will automatically convert into shares of Series C Stock upon (i) the closing of a private placement of equity securities of the Company in one or more transactions with gross proceeds

to the Company totaling at least $5 million, before deduction of commissions and expenses, or (ii) upon an acquisition of the Company or of all or substantially all of its assets. Each share of Series C Stock by its terms is initially convertible into 40 shares of the Company’s common stock (“Common Stock”) at a conversion price of $2.25 per share. The Conversion Price of the Series C Stock is subject to adjustment as provided in the Certificate of Designation for the Series C Stock.

The Company will also issue to each purchaser of a Note a warrant to purchase 10,000 shares of Common Stock for every $100,000 in principal of the Note. The warrants are exercisable for a period of five years from the date of issuance. The initial warrant exercise price is $2.25 per share and is subject to adjustment if the Company issues securities at a price of less than $2.25 per share, subject to customary exceptions, as set forth in the warrant. The purchasers of the Notes are also entitled to demand and piggyback registration rights with respect to the shares of Common Stock underlying the Series C Stock issuable upon conversion of the Note and the Common Stock issuable upon exercise of the warrants.

In connection with the bridge financing, the Company executed an Agency Agreement with Fleming Securities, Inc. (the “Agent”) and agreed to: (i) pay the Agent, a selling commission equal to 10% of the gross proceeds from the sales of the Notes and warrants sold in this bridge financing; (ii) sell to the Agent, for nominal consideration, ten-year warrants to purchase Common Stock at 120% of the exercise price of the warrants sold in this bridge financing, a number of shares of Common Stock equal to 10% of the number of shares of Common Stock that may be purchased pursuant to warrants sold in this bridge financing; (iii) pay the Agent a non-accountable expense allowance equal to 3% of the gross proceeds from sales of Notes and warrants in this bridge financing; and (iv) reimburse the Agent for its accountable expenses of this bridge financing not to exceed $50,000.

Section 4(k) — Litigation. See disclosure contained in Section 4(g).

Section 4(m) - Brokers or Finders. The Company has issued to Fleming Securities, Inc. a 5-year warrant or warrants, as the case may be, to purchase 300,084 shares of common stock with respect to an initial investment and conversions totaling $6,751,909.31. Also, with respect to additional purchases of Series C Preferred Stock under the Stock Purchase Agreement, the Company has agreed to issue Fleming Securities, Inc. a warrant or warrants for a number of shares of common stock equal to 10% of the shares issuable upon conversion of the Series C Preferred Stock sold through Fleming Securities, Inc. to Investors, at an exercise price equal to $2.70 per share. To date, The Company has issued Fleming Securities a 5-year warrant for 13,336 shares of the Company’s common stock, par value $0.01, at a per share exercise price of $2.70. As of March 15, 2005 Fleming Securities earned, but had not been issued, additional warrants to purchase 102,228 shares of common stock at that exercise price.

EX-2

Exhibit 2

NOTE AND WARRANT PURCHASE AGREEMENT

     THIS NOTE AND WARRANT PURCHASE AGREEMENT (“Agreement”) is made and entered into effective as of March 15, 2006, by and among Optical Sensors Incorporated, a Delaware corporation d/b/a väsamed (the “Company”), with its principal place of business at 7615 Golden Triangle Drive, Suite A, Eden Prairie, Minnesota 55344, and the Hayden R. Fleming and LaDonna M. Fleming Revocable Trust (the “Investor”). Investor has an office at the address set forth on the signature page hereto.

     A. The Company currently needs up to an aggregate of Four Million Five Hundred Thousand Dollars ($4,500,000) to fund its operation until such time as it is able raise additional equity capital (the “Bridge Financing”).

     B. The Investor desires to participate in the Bridge Financing with other investors (the “Other Investors”) and purchase a convertible promissory note and warrant from the Company on the terms and conditions set forth in this Agreement.

     Accordingly, in consideration of the foregoing, the mutual promises set forth herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

1. (a) Purchase of Convertible Promissory Note. Upon the terms and subject to the conditions set forth in this Agreement, the Company agrees to issue to the Investor, and the Investor agrees to purchase from the Company, a convertible promissory note in the form attached hereto as Exhibit A in the principal amount of One Hundred Thousand Dollars ($100,000) (the “Note” and collectively, with the other notes issued in the Bridge Financing to the Other Investors, the “Notes”). The Note shall bear interest at the rate of ten percent (10%) per annum from the date of the Note until paid in full and shall be due and payable in full eighteen (18) months from the date of issuance (the “Maturity Date”) unless converted into shares of Series C Preferred Stock (“Series C Stock”) of the Company prior to the Maturity Date. The Company shall have the right to prepay the Note, in whole or in part, without premium or penalty, at any time or from time to time, on ten (10) days’ prior written notice to the Investor. The Note, along with the other Notes, shall be secured by a lien on the assets of the Company, except for patents and other rights to intellectual property and regulatory approvals held by the Company. The terms of such lien and exceptions are set forth in the Security Agreement attached hereto as Exhibit D, which will be executed by the Investor together with the Other Investors.

(b) Issue of Warrants. As part of this transaction, Company will issue to Investor a warrant to purchase 10,000 shares of the Company’s common stock (“Common Stock”) for every One Hundred Thousand Dollars ($100,000) in principal of the Note or portion thereof, pro-rata, which warrant (the “Warrant”) will be in substantially the form attached hereto as Exhibit B and will have an initial

exercise price equal to $2.25 per share, subject to adjustment of the exercise price and number of shares purchasable as set forth in the Warrant. The Warrant issued to the Investor, along with warrants issued to Other Investors, are a part of a series of warrants for rights to purchase up to Four Hundred Fifty Thousand (450,000) shares of Common Stock (the “Warrants”) The Warrant shall be exercisable for a period of five (5) years from the date of issuance. The shares issuable upon the exercise of the Warrant are referred to as the “Warrant Shares”. The Note and Warrant, collectively, are referred to herein as the “Securities”.

2. (a) Voluntary Conversion.The Investor shall have the right to convert all or any portion of principal balance of the Note, at the option of the Investor, into shares of the Series C Stock at any time, and from time to time. All accrued and unpaid interest on any principal so converted shall, at the Company’s option, be paid (i) in shares of Series C Stock at the time of conversion, or (ii) in cash in accordance with the interest provisions of the Note. The conversion price of the Note shall be $90.00 per share of Series C Stock. A copy of the Certificate of Designation for the Series C Stock is attached hereto as Exhibit C. The shares of Series C Stock issuable upon conversion of the Note are referred to as the “Conversion Securities”.

(b) Automatic Conversion. All outstanding principal under the Note will automatically convert into shares of Series C Preferred stock, at the $90.00 per share conversion price, upon (i) the closing of a private placement of equity securities of the Company in one or more transactions with gross proceeds to the Company totaling at least $5 million, before deduction of agent’s commissions and expenses, or (ii) upon an acquisition of the Company or of all or substantially all of its assets. All accrued and unpaid interest on any principal so converted shall, at the Company’s option, be paid (i) in shares of Series C Stock at the time of conversion, or (ii) in cash in accordance with the interest provisions of the Note.

3. Representations and Warranties of the Investor. The Investor represents and warrants to, and covenants with the Company as follows:

     (a) The Investor qualifies as an “accredited investor,” as defined in Rule 501 of Regulation D under the Securities Act. Specifically, (check all that apply):

     INDIVIDUALS

— A. The undersigned is an individual with a net worth, or a joint net worth together with his or her spouse, in excess of $1,000,000. (In calculating net worth, you may include equity in personal property and real estate, including your principal residence, cash, short-term investments, stock and securities. Equity in personal property and real estate should be based on the fair market value of such property minus debt secured by such property.)

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—	B.	The undersigned is an individual (not a partnership, corporation, etc.) with income in excess of $200,000 in each of the prior two years and reasonably expects an income in excess of $200,000 in the current year.
—	C.	The undersigned is an individual (not a partnership, corporation, etc.) who, with his or her spouse, had joint income in excess of $300,000 in each of the prior two years and reasonably expects joint income in excess of $300,000 in the current year.
—	D.	The undersigned is a director or executive officer of the Company.
ENTITIES
—	E.	The undersigned, if other than an individual, is an entity all of whose equity owners meet one of the tests set forth in (a) through (d) above (if relying on this category alone, each equity owner must complete a separate copy of this Agreement).
—	F.	The undersigned is an entity, and is an “Accredited Investor” as defined in Rule 501(a) of Regulation D under the Act. This representation is based on the following (check one or more, as applicable):

—	1.	The undersigned (or, in the case of a trust, the undersigned trustee) is a bank or savings and loan association as defined in Sections (a)(2) and 3(a)(5)(A), respectively, of the Act acting either in its individual or fiduciary capacity.
—	2.	The undersigned is an insurance company as defined in Section 2(13) of the Act.
—	3.	The undersigned is an investment company registered under the Investment Company Act of 1940 or a business development company as defined in Section 2(a)(48) of that Act.
—	4.	The undersigned is a Small Business Investment Company licensed by the U.S. Small Business Administration under Section 301(c) or (d) of the Small Business Investment Act of 1958.
—	5.	he undersigned is an employee benefit plan within the meaning of Title I of the Employee Retirement Income Security Act of 1974 (“ERISA”) and either (check all that apply):

— a. the investment decision is made by a plan fiduciary, as defined in Section 3(21) of ERISA, which is either a bank, savings and

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		loan association, insurance company, or registered investment adviser; or
—	b.	the employee benefit plan has total assets in excess of $5,000,000; or
—	c.	the plan is a self-directed plan with investment decisions made solely by persons who are “Accredited Investors” as defined under the Act.

—	6.	The undersigned is a private business development company as defined in Section 202(a)(22) of the Investment Advisers Act of 1940.
—	7.	The undersigned has total assets in excess of $5,000,000, was not formed for the specific purpose of acquiring securities of the Company and is one or more of the following (check one or more, as appropriate):

—	a.	an organization described in Section 501(c)(3) of the Internal Revenue Code; or
—	b.	a corporation; or
—	c.	a Massachusetts or similar business trust; or
—	d.	a partnership.

X — 8. The undersigned is a trust with total assets exceeding $5,000,000 which was not formed for the specific purpose of acquiring securities of the Company and whose purchase is directed by a person who has such knowledge and experience in financial and business matters that he is capable of evaluating the merits and risks of the investment in the Securities.

Paragraph 3(a) is required in connection with the exemptions from the Act and State Laws being relied on by the Company with respect to the offer and sale of the Securities.

The undersigned agrees to furnish any additional information which the Company or its legal counsel deem necessary in order to verify the responses set forth above.

(b) The Note and Warrant are being purchased for investment for the Investor’s own account and not with the view to, or for resale in connection with, any distribution or public offering thereof. The Investor understands that neither the Note, the Warrant, the Warrant Shares nor the Conversion Securities have been registered under the Securities Act or any state securities laws by reason of their

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	contemplated issuance in transactions exempt from the registration requirements of the Securities Act and applicable state securities laws and that the reliance of the Company and others upon these exemptions is predicated in part upon this representation by the Investor. The Investor further understands that the Note, the Warrant, the Warrant Shares and the Conversion Securities may not be transferred or resold without registration under the Securities Act and any applicable state securities laws, or pursuant to an exemption from the requirements of the Securities Act and applicable state securities laws.
(c)	The Investor acknowledges that the Company has made available to the Investor prior to the execution of this Agreement the materials listed in Exhibit E attached hereto; the Investor has received all materials that have been requested by Investor and Investor has had the opportunity to ask questions and receive answers concerning the business, operations and financial condition of the Company and the terms and conditions of the sale of securities contemplated by this Agreement and to obtain any additional information requested by such Investor. The Investor understands the risks of an investment in the Company as proposed herein and is able to bear such risks, including the loss of its entire investment in the Note, the Warrant, the Warrant Shares and the Conversion Securities. The Investor has such knowledge and experience of financial and business matters that he is capable of evaluating the merits and risks of the investment to be made pursuant to this Agreement.
(d)	This Agreement has been duly authorized by all necessary action on the part of the Investor, has been duly executed and delivered by such Investor and is a valid and binding agreement of such Investor.

4. Representations and Warranties of the Company. The Company represents and warrants to the Investor as follows:

(a)

Organization. The Company is a corporation duly organized, validly existing and in good standing under the laws of the State of Delaware and has the requisite corporate power and authority to own, lease or operate its properties and to carry on its business as it is now being conducted and as it is proposed to be conducted. The Company has no subsidiaries or direct or indirect ownership in any firm, corporation or business which either, individually or in the aggregate, is material to the business of the Company. The Company is qualified to do business and is in good standing as a foreign corporation in every jurisdiction in which its ownership of property or conduct of business requires it so to be qualified and in which the failure to so qualify would have a material adverse effect on the financial condition or business of the Company.

(b)

Authorization. The Company has the corporate power and authority to execute and deliver this Agreement, the Securities and the Conversion Securities and to perform its obligations hereunder and thereunder. This Agreement, the Securities, the Warrant Shares and the Conversion Securities have been duly authorized by all necessary corporate action on behalf of the Company, have been duly executed

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	and delivered by authorized officers of the Company, are valid and binding agreements on the part of the Company and are enforceable against the Company in accordance with their respective terms, except as the enforceability thereof may be limited by bankruptcy, insolvency, moratorium, reorganization or other similar laws affecting the enforcement of creditors rights generally and to judicial limitations on the enforcement of the remedy of specific performance and other equitable remedies. All corporate actions necessary for reservation and issuance of the Conversion Securities and the Warrant Shares has been taken. The Conversion Securities and the Warrant Shares when issued pursuant to conversion of the Note or the exercise of the Warrant will be duly authorized, validly issued, fully paid and nonassessable, free and clear of any and all liens, charges, claims, encumbrances and preemptive rights.
(c)	No Violation. Neither the execution and delivery of this Agreement, the Securities, the Warrant Shares and the Conversion Securities by the Company, nor the performance by the Company of its obligations hereunder or thereunder, nor the consummation of the transactions contemplated hereby or thereby will: (a) conflict with or result in any breach of any provision of the Certificate of Incorporation or By-Laws of the Company; (b) result in a default (or give rise to any right of termination, cancellation or acceleration) under any of the terms, conditions or provisions of any note, lease, mortgage, license, agreement or other instrument or obligation to which the Company is a party or by which any of its assets may be bound, except for such defaults (or rights of termination, cancellation or acceleration) as to which requisite waivers or consents have been obtained or which, in the aggregate, would not result in a material adverse effect on the Company; (c) violate any order, writ, injunction, decree, statute, rule or regulation applicable to the Company or any of its assets, except for violations which would not result in a material adverse effect on the Company; or (d) result in the creation or imposition of any liens, charges or encumbrances upon any assets of the Company.
(d)	SEC Reports. The Company has filed all reports, registration statements and other filings with the Securities and Exchange Commission (the “Commission”) required to be filed by it pursuant to the Securities Act of 1933, as amended (the “Securities Act”), and the Securities Exchange Act of 1934, as amended (the “Exchange Act”). All such reports, registration statements and other filings (including all notes, exhibits and schedules thereto, all documents incorporated by reference therein, and any amendments thereto) are collectively referred to herein as the “SEC Reports.” As of their respective dates of filing with the Commission, the SEC Reports complied in all material respects with all of the rules and regulations of the Commission and did not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements made therein, in light of the circumstances under which they were made, not misleading.
(e)	Financial Statements. The financial statements of the Company included in the SEC Reports (the “Financial Statements”) have been prepared in accordance with

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	United States generally accepted accounting principles consistently applied and fairly present the financial position of the Company at the dates thereof and the results of the Company’s operations and cash flows for the periods then ended (subject, in the case of unaudited statements, to normal adjustments and the omission of footnotes). The Company has no material liabilities, known or unknown, absolute, contingent or otherwise, except for (i) those liabilities that are required to be set forth in the Financial Statements, the notes thereto or the SEC Reports pursuant to generally accepted accounting principles, and (ii) liabilities that have been incurred in the ordinary course of business since September 30, 2005.
(f)	No Material Adverse Change. There have not been any changes in the assets, properties, liabilities, financial condition, business or operations of the Company from that reflected in the Financial Statements except for (i) changes in the ordinary course of business which have not been, either individually or in the aggregate, materially adverse and (ii) the Company’s continued operating losses and negative cash flow.
(g)	Authorized Capital Stock. The authorized capital stock of the Company is 30,000,000 shares of Common Stock, $0.01 par value per share, and 5,000,000 shares of preferred stock, $0.01 par value per share. 4,333,334 preferred shares have been designated as Series A Convertible Preferred Stock, 250,000 preferred shares have been designated as Series B Convertible Preferred Stock, 166,666 preferred shares have been designated as Series C Convertible Preferred Stock and 250,000 preferred shares have been designated as Series A Junior Preferred Stock. There are currently issued and outstanding 3,808,289 shares of Common Stock, 4,333,334 shares of Series A Preferred, 236,934 shares of Series B Preferred and 100,021 shares of Series C Preferred. Collectively, the preferred shares are convertible into 5,907,732 shares of Common Stock. The issued and outstanding shares of capital stock of the Company have been duly authorized, validly issued and are fully paid and nonassessable. As of the date hereof, the Company has outstanding options and warrants to purchase 842,588 shares and 488,419 shares, respectively, of Common Stock. Except as set forth in the preceding sentence, there are no other outstanding warrants, options or other rights to acquire any shares of capital stock of the Company, except for the Conversion Securities issued upon conversion of the Notes, the Warrant Shares issued upon the exercise of the Warrants, the warrant (and related underlying shares of common stock) issued to Fleming Securities, Inc. issued in connection with this Bridge Financing and as disclosed in the SEC Reports. All of the above securities of the Company were issued in compliance with all applicable federal and state securities laws and were not issued in violation of or subject to any preemptive rights or other rights to subscribe for or purchase securities.
(h)	Intellectual Property. The Company owns or possesses adequate rights to use all patents, patent rights, inventions, trademarks, trade names, copyrights, licenses, domain names, governmental authorizations, trade secrets and know-how that are used or necessary for the conduct of its business; the Company has not received

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	any notice of, and has no knowledge of, any infringement of or conflict with asserted rights of others with respect to any patents, patent rights, inventions, trademarks, trade names, copyrights, licenses, governmental authorizations, trade secret or know-how that, individually or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would have a material adverse effect on the condition (financial or otherwise), earnings, operations or business of the Company and its subsidiaries considered as a whole.
(i)	Securities Laws. Subject to the accuracy of the representations of the Investor in Section 3, no consent, authorization, approval, permit or order of or filing with any governmental or regulatory authority is required under current laws and regulations in connection with the execution and delivery of this Agreement or the offer, issuance, sale or delivery to the Investor of the Note, the Warrant, the Warrant Shares or the Conversion Securities other than the filing with the Commission of a Form D pursuant to Regulation D under the Securities Act, and the qualification thereof, if required, under applicable state securities laws, which qualification has been or will be effected as a condition of the sale of the Securities and the issuance of the Conversion Securities and Warrant Shares.
(j)	Litigation. There are no actions, suits, proceedings or investigations pending or, to the best of the Company’s knowledge, threatened against the Company or any of its properties before or by any court or arbitrator or any governmental body, agency or official in which there is a reasonable likelihood (in the judgment of the Company) of an adverse decision that (a) would have a material adverse effect on the Company’s properties or assets or the business of the Company as presently conducted or proposed to be conducted or (b) would impair the ability of the Company to perform in any material respect its obligations under this Agreement. The Company is not in default with respect to any judgment, order or decree of any court or governmental agency or instrumentality which, individually or in the aggregate, would have a material adverse effect on the assets, properties or business of the Company.

5. Registration Rights. The Company shall register the Warrant Shares and the Common Stock underlying the Conversion Securities with the Securities and Exchange Commission on any registration statement filed by the Company pursuant to Section 6 of the Stock Purchase Agreement, dated as of May 6, 2005, between the Company and the Series C Investors listed therein.

6. Miscellaneous.

(a)	The Company will file with the Commission, on a timely basis, all SEC Reports required to be filed under the Exchange Act and any other documents required to meet the public information requirements of Rule 144(c) under the Securities Act.
(b)	This Agreement and the rights and obligations of the parties hereunder shall not be assignable by the Investor, in whole or in part, except by operation of law.

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	This Agreement shall inure to the benefit of and be binding upon and be enforceable by the successors and permitted assigns of the parties hereto.
(c)	Neither this Agreement nor any provision hereof may be amended, modified, waived or discharged without the written consent of the parties hereto.
(d)	This Agreement, including the exhibits attached hereto, constitutes the entire agreement of the parties relative to the subject matter hereof and supersedes any and all other agreements and understanding, whether written or oral, relative to the matters discussed herein.
(e)	All representations and warranties contained herein shall survive after the execution and delivery of this Agreement for a period of one (1) year from the date hereof. All covenants and agreements which by their terms are to be performed after the date hereof will survive indefinitely, unless such covenants and agreements by their terms expire at an earlier date, in which case they will expire on such earlier date.
(f)	All notices, requests, consents and other communications required or permitted hereunder shall be in writing and shall be given in writing by personal delivery, facsimile, commercial air delivery service or by registered or certified mail, postage prepaid, return receipt requested, addressed to the Company at the address set forth in the introductory paragraph to this Agreement and to the Investor at the address set forth on the signature page hereto, or at such other address as the respective parties may designate by like notice from time to time. Notices so given shall be effective upon the earlier of: (a) receipt by the party to which notice is given (which, in the instance of a facsimile, shall be deemed to have occurred at the time that the machine transmitting the facsimile verifies a successful transmission of the facsimile); (b) on the fifth business day following the date such notice was deposited in the mail; or (c) on the second business day following the date such notice was delivered to a commercial air delivery service.
(g)	This Agreement shall be construed and enforced in accordance with the laws of the State of Minnesota.
(h)	This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. This Agreement may be executed by facsimile.

[NEXT PAGE IS SIGNATURE PAGE]

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     IN WITNESS WHEREOF, the Company and the Investor have executed this Agreement effective as of the date first written above.

Principal Amount of Note Being Purchased: $ 100,000     
(Aggregate Purchase Price of the Note is the Principal Amount of the Note)

Hayden R. Fleming and LaDonna M. Fleming Revocable Trust     
Print Name of Investor

     Hayden R. Fleming /s/      
Signature of Investor — Trustee

IMPORTANT — INVESTOR MUST INITIAL
THE APPROPRIATE REPRESENTATION
IN SECTION 3(a) ABOVE BEFORE THE
COMPANY WILL CONSIDER THIS
SUBSCRIPTION.

Social Security Number/ Taxpayer
Identification Number:
 471 56 9619          

Address:  17797 N. Perimeter Drive, Suite 105

                     Scottsdale, AZ 85255                    

If the Note will be held as joint tenants, tenants
in common or community property, please
complete the following:

                                                                               
Print name of spouse or other co-subscriber

                                                                                 
Signature of spouse or other co-subscriber

                                                                                 
Print the manner in which securities to be held

                                                                                 
Social Security number of co-subscriber

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ACCEPTED BY:
OPTICAL SENSORS INCORPORATED		Date:	March 15, 2006
By	Paulita LaPlante /s/
	Paulita LaPlante, President and CEO

Exhibits:

A — Promissory Note

B — Warrant to purchase Series C Stock

C — Security Agreement

D — Certificate of Designation — Series C Preferred Stock

E — List of materials delivered to Investor

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