Balance Sheets (USD $)	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 13,622,445	$ 16,986,809
Accounts receivable, net	1,056,932	1,592,564
Inventories	1,739,724	2,412,805
Prepaid expenses and other current assets	415,370	603,821
Current portion of deferred costs	54,332	81,194
Total current assets	16,888,803	21,677,193
Restricted cash	229,500	408,000
Fixed assets, net	625,729	731,975
Intangible assets, net		210,000
Deferred costs and other long-term assets	15,610	39,261
Total assets	17,759,642	23,066,429
Current liabilities:
Accounts payable	174,870	259,155
Accrued compensation	748,893	683,049
Accrued expenses	973,438	1,227,790
Current portion of deferred revenue	312,880	468,324
Current portion of capital lease obligation	19,493	19,093
Total current liabilities	2,229,574	2,657,411
Deferred revenue, net of current portion	84,695	171,797
Capital lease obligation, net of current portion	26,840	38,249
Total liabilities	2,341,109	2,867,457
Commitments and contingencies (Notes 7 and 9)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized, none outstanding
Common stock, $0.0001 par value; 50,000,000 shares authorized; 23,344,141 and 23,197,537 shares issued and outstanding at June 30, 2011 and December 31, 2010, respectively	2,334	2,320
Additional paid-in capital	139,154,459	138,800,937
Accumulated deficit	(123,738,260)	(118,604,285)
Total stockholders' equity	15,418,533	20,198,972
Total liabilities and stockholders' equity	$ 17,759,642	$ 23,066,429