Stockholders' equity (Details Textual)							1 Months Ended			3 Months Ended	6 Months Ended	9 Months Ended		25 Months Ended
	Apr. 19, 2018 shares	Feb. 06, 2018 USD ($) $ / shares shares	Jan. 17, 2018 shares	Jan. 01, 2018 shares	Jul. 18, 2017 USD ($) $ / shares shares	Sep. 13, 2016 USD ($)	Oct. 31, 2017 USD ($) shares	Sep. 30, 2017 USD ($) shares	Jul. 31, 2017 USD ($)	Sep. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2018	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) shares	Jan. 16, 2018 shares	Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized			50,000,000							50,000,000		50,000,000		50,000,000	200,000,000	50,000,000
Common stock, shares issued										6,425,470		6,425,470		6,425,470		2,265,320
Common stock, shares outstanding										6,425,470		6,425,470		6,425,470		2,265,320
Preferred stock, shares authorized										10,000,000		10,000,000		10,000,000		10,000,000
Preferred stock, shares issued										0		0		0		0
Preferred stock, shares outstanding										0		0		0		0
Proceeds from issuance of common stock, net of issuance costs | $												$ 597,743	$ 3,426,050
Net proceeds from sale of common stock and warrants | $												$ 10,728,132	$ 8,754,882
Stock split												On January 17, 2018, the Company filed an amendment to its Amended and Restated Certificate of Incorporation to effect a reverse stock split of the issued and outstanding shares of common stock, at a ratio of one share for twenty-five shares, and to reduce the authorized shares of common stock from 200,000,000 to 50,000,000 shares. All share amounts and per share prices in this quarterly report have been adjusted to reflect the reverse stock split.
Reverse stock split conversion ratio			0.04
Share-based compensation, tax benefit from compensation expense | $												$ 0
Stock options, granted										0		95,800
Stock options, granted, weighted average exercise price | $ / shares												$ 3.84
Stock options, granted, weighted average grant date fair value | $ / shares												$ 1.93
Stock options, forfeited										7,120		13,336
Stock options, forfeited, weighted average exercise price | $ / shares										$ 5.61		$ 13.36
Stock options, outstanding										218,759		218,759		218,759
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period												5,400
Share-based compensation arrangement by share-based payment award, equity instruments other than options, forfeited in period												0
Share-based compensation arrangement by share-based payment award, equity instruments other than options, non-vested, outstanding										500		500		500
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized										54,200		54,200		54,200
Share-based compensation arrangement by share-based payment award, description												the number of shares that have been authorized for issuance under the 2015 Plan will be automatically increased on the first day of each fiscal year beginning on January 1, 2016 and ending on (and including) January 1, 2025, in an amount equal to the lesser of (1) 4% of the outstanding shares of common stock on the last day of the immediately preceding fiscal year, or (2) another lesser amount determined by the Company’s Board of Directors.
Share-based compensation arrangement by share-based payment award, number of shares available for grant										43,658		43,658		43,658
Share-based compensation arrangement by share-based payment award, common stock percentage												4.00%
Share-based compensation arrangement by share-based payment award, number of additional shares added				90,612
Common Stock [Member] | Pre-Merger Dispute Settlement [Member] | AdvanDx [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, value, new issues | $								$ 110,000
Stock issued during period, shares, new issues								15,842
Common Stock [Member] | Vendor Consulting Services [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, value, new issues | $							$ 23,245
Stock issued during period, shares, new issues							2,898
At the Market Offering [Member] | Sales Agreement [Member] | Cowen and Company, LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate gross proceeds from issuance of common stock | $												$ 9,400,000		$ 9,400,000
Stock issued during period, value, new issues | $						$ 11,500,000
Maximum commission percentage on gross proceeds						3.00%
Aggregate net proceeds from issuance of common stock | $												8,800,000		$ 8,800,000
Proceeds from issuance of common stock, net of issuance costs | $										$ 400,000		600,000
Gross proceeds from sale of common stock | $										$ 400,000		$ 600,000
At the Market Offering [Member] | Sales Agreement [Member] | Maximum [Member] | Cowen and Company, LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate gross proceeds from issuance of common stock | $						$ 25,000,000
At the Market Offering [Member] | Common Stock [Member] | Sales Agreement [Member] | Cowen and Company, LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues										214,193		318,236		690,247
October 2018 Public Offering [Member] | Sales Agreement [Member] | Cowen and Company, LLC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unsold shares under terminated at the market offering | $												$ 2,075,318
July 2017 Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues					18,164,195
Shares issued, price per share | $ / shares					$ 0.40
Gross proceeds from sale of common stock and warrants | $					$ 10,000,000
Net proceeds from sale of common stock and warrants | $					$ 8,800,000
Sale of stock, description of transaction												Each unit included one twenty-fifth of a share of common stock and one common warrant to purchase one twenty-fifth of a share of common stock at an exercise price of $10.63 per share. Each pre-funded unit included one pre-funded warrant to purchase one twenty-fifth of a share of common stock for an exercise price of $0.25 per share, and one common warrant to purchase one twenty-fifth of a share of common stock at an exercise price of $10.63 per share.
Class of warrant or right, number of securities called by each warrant or right					0.04
Class of warrant or right, exercise price of warrants or rights | $ / shares					$ 10.63
Warrants exercisable period					5 years
July 2017 Public Offering [Member] | Placement Agent [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, exercise price of warrants or rights | $ / shares					$ 12.50
Warrants exercisable period					5 years
July 2017 Public Offering [Member] | Bridge Financing Notes [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repayment of principal amount of outstanding debt | $					$ 1,000,000				$ 1,000,000
Repayments of accrued interest on outstanding debt | $					$ 6,438
July 2017 Public Offering [Member] | Common Stock [Member] | Placement Agent [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, number of securities called by warrants or rights					50,000
July 2017 Public Offering [Member] | Pre-funded Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues					6,835,805
Shares issued, price per share | $ / shares					$ 0.39
July 2017 Public Offering [Member] | Pre-funded Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, number of securities called by each warrant or right					0.04
Class of warrant or right, exercise price of warrants or rights | $ / shares					$ 0.25
February 2018 Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues		2,841,152
Shares issued, price per share | $ / shares		$ 3.25
Gross proceeds from sale of common stock and warrants | $		$ 12,000,000
Net proceeds from sale of common stock and warrants | $		$ 10,700,000
Sale of stock, description of transaction											Each unit included one share of common stock and one common warrant to purchase 0.5 share of common stock at an exercise price of $3.25 per share. Each pre-funded unit included one pre-funded warrant to purchase one share of common stock for an exercise price of $0.01 per share, and one common warrant to purchase 0.5 share of common stock at an exercise price of $3.25 per share.	Each unit included one share of common stock and one common warrant to purchase 0.5 share of common stock at an exercise price of $3.25 per share. Each pre-funded unit included one pre-funded warrant to purchase one share of common stock for an exercise price of $0.01 per share, and one common warrant to purchase 0.5 share of common stock at an exercise price of $3.25 per share.
Class of warrant or right, number of securities called by each warrant or right		0.5
Class of warrant or right, exercise price of warrants or rights | $ / shares		$ 3.25
Warrants exercisable period		5 years
February 2018 Public Offering [Member] | Placement Agent [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, exercise price of warrants or rights | $ / shares		$ 4.0625
Warrants exercisable period		5 years
February 2018 Public Offering [Member] | Common Stock [Member] | Placement Agent [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, number of securities called by warrants or rights		184,615
February 2018 Public Offering [Member] | Pre-funded Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues		851,155
Shares issued, price per share | $ / shares		$ 3.24
February 2018 Public Offering [Member] | Pre-funded Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of warrant or right, exercise price of warrants or rights | $ / shares		$ 0.01
Warrants exercised	851,155											851,155