Stockholders' equity (Tables)

9 Months Ended

Sep. 30, 2016

Stockholders Equity Note [Abstract]

Schedule of allocation of share-based compensation expense

For the three and nine months ended September 30, 2016 and 2015, the Company recognized stock compensation expense as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Cost of services	$	—	$	—	$	5,008	$	—
Research and development		45,945		59,688		181,367		161,819
General and administrative		98,683		156,236		447,811		443,267
Sales and marketing		34,124		45,616		72,462		567,145
	$	178,752	$	261,540	$	706,648	$	1,172,231

Schedule of warrants to purchase shares of common stock

Stock purchase warrants

At September 30, 2016, the following warrants to purchase shares of common stock were outstanding:

Issuance	Exercise Price		Expiration	Shares of Common Stock Subject to Warrants
August 2007	$	7.91	August 2017		8,921
March 2008	$	790.54	March 2018		46
November 2009	$	7.91	November 2019		6,674
January 2010	$	7.91	January 2020		6,674
March 2010	$	7.91	March 2020		1,277
November 2011	$	7.91	November 2021		5,213
December 2011	$	7.91	December 2021		664
March 2012	$	109.90	March 2019		4,125
February 2015	$	6.60	February 2025		225,011
May 2015	$	6.60	May 2020		3,457,750
May 2016	$	1.31	May 2021		4,739,348
June 2016	$	1.31	May 2021		2,050,821
					10,506,524