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	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2016	$ (5,592,862)			$ 7,938			$ 110,081,334			$ (75,000)	$ (1,090)	$ (115,606,044)
Balance, shares at Dec. 31, 2016				7,938,571
Exercise of stock options	112,138			$ 42			112,096
Exercise of stock options, shares				41,815
Stock-based compensation expense	1,376,633						1,376,633
Release of restricted stock awards	336			$ 336
Release of restricted stock awards, shares				336,333
Stock issued under stock purchase plan	$ 325,667			$ 141			325,526
Stock issued under stock purchase plan, shares	61,141			141,082
Issuance of common stock		$ 19,677,478			$ 5,472			$ 19,672,006
Issuance of common stock, shares					5,471,962
Retirement of Treasury shares							(75,000)			$ 75,000
Net loss	$ (18,960,017)											(18,960,017)
Unrealized gain (loss) on short-term investments	1,090										1,090
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	316,767			$ 145			316,622
Exercise of stock options, shares				144,645
Stock-based compensation expense	1,887,764						1,887,764
Release of restricted stock awards	291			$ 291
Release of restricted stock awards, shares				291,010
Net share settlement of restricted stock awards	(150,748)			$ (39)			(150,709)
Net share settlement of restricted stock awards, shares				(38,582)
Stock issued under stock purchase plan	$ 199,874			$ 82			199,792
Stock issued under stock purchase plan, shares	2,304			82,261
Issuance of common stock		$ 556,706	$ 37,724,316		$ 262	$ 13,915		$ 556,444	$ 37,710,401
Issuance of common stock, shares					261,352	13,915,000
Issuance of common stock warrants in connection with MidCapTerm Loan	$ 74,000						74,000
Net loss	(16,453,918)											(16,453,918)
Unrealized gain (loss) on short-term investments	(2,308)										(2,308)
Foreign currency translation adjustment	(1,145)										(1,145)
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