Condensed Consolidated Statements of Changes in Stockholders' Equity (Deficit) - USD ($)	Total	ATM Offering	Underwritten Public Offering	Common Stock	Common Stock ATM Offering	Common Stock Underwritten Public Offering	Additional Paid-In Capital	Additional Paid-In Capital ATM Offering	Additional Paid-In Capital Underwritten Public Offering	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2017	$ (3,059,537)			$ 13,929			$ 131,492,595				$ (134,566,061)
Balance, shares at Dec. 31, 2017				13,929,763
Exercise of stock options	40,504			$ 18			40,486
Exercise of stock options, shares				18,028
Stock-based compensation expense	1,143,188						1,143,188
Release of restricted stock awards	270			$ 270
Release of restricted stock awards, shares				269,551
Net share settlement of restricted stock award	(133,513)			$ (35)			(133,478)
Net share settlement of restricted stock award, shares				(34,769)
Employee stock purchase plan expense	$ 14,453						14,453
Issuance of common stock		$ 556,706	$ 37,724,316		$ 262	$ 13,915		$ 556,444	$ 37,710,401
Issuance of common stock, shares	5,733,314			261,352	261,352	13,915,000
Issuance of common stock warrants in connection with MidCapTerm Loan	$ 74,000						74,000
Net loss	(5,379,947)										(5,379,947)
Unrealized gain (loss) on short-term investments	(11,151)									$ (11,151)
Balance at Mar. 31, 2018	30,969,289			$ 28,359			170,898,089			(11,151)	(139,946,008)
Balance, shares at Mar. 31, 2018				28,358,925
Balance at Dec. 31, 2018	21,092,062			$ 28,585			172,086,909			(3,453)	(151,019,979)
Balance, shares at Dec. 31, 2018				28,585,449
Exercise of stock options	51,570			$ 22			51,548
Exercise of stock options, shares				21,871
Stock-based compensation expense	241,233						241,233
Release of restricted stock awards	13			$ 13
Release of restricted stock awards, shares				13,126
Net share settlement of restricted stock award	(9,685)			$ (4)			(9,681)
Net share settlement of restricted stock award, shares				(3,813)
Employee stock purchase plan expense	16,794						16,794
Net loss	(5,370,846)										(5,370,846)
Unrealized gain (loss) on short-term investments	3,353									3,353
Foreign currency translation adjustment	6,439									6,439
Balance at Mar. 31, 2019	$ 16,030,933			$ 28,616			$ 172,386,803			$ 6,339	$ (156,390,825)
Balance, shares at Mar. 31, 2019				28,616,633