Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Total	LP Purchase Agreement	ATM Offering	Private Placement	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock Private Placement	Common Stock	Common Stock LP Purchase Agreement	Common Stock ATM Offering	Additional Paid-In Capital	Additional Paid-In Capital LP Purchase Agreement	Additional Paid-In Capital ATM Offering	Additional Paid-In Capital Private Placement	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
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
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
Net loss	(14,908,348)
Unrealized gain (loss) on short-term investments	2,308
Balance at Sep. 30, 2019	28,116,504						$ 58,031			193,953,125				33,675	(165,928,327)
Balance, shares at Sep. 30, 2019							58,031,230
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
Exercise of stock options	69,384						$ 32			69,352
Exercise of stock options, shares							32,385
Stock-based compensation expense	287,317									287,317
Release of restricted stock awards	15						$ 15
Release of restricted stock awards, shares							15,001
Net share settlement of restricted stock award	(11,152)						$ (4)			(11,148)
Net share settlement of restricted stock award, shares							(4,461)
Stock issued under stock purchase plans	99,140						$ 48			99,092
Stock issued under stock purchase plans, shares							47,489
Net loss	(4,797,270)														(4,797,270)
Unrealized gain (loss) on short-term investments	819													819
Foreign currency translation adjustment	(9,194)													(9,194)
Balance at Jun. 30, 2019	11,669,992						$ 28,707			172,831,416				(2,036)	(161,188,095)
Balance, shares at Jun. 30, 2019							28,707,047
Stock-based compensation expense	316,525									316,525
Release of restricted stock awards	30						$ 30
Release of restricted stock awards, shares							30,001
Net share settlement of restricted stock award	(7,230)						$ (5)			(7,225)
Net share settlement of restricted stock award, shares							(4,355)
Employee stock purchase plan expense	16,325									16,325
Issuance of common stock and warrants from the public and private offerings, net of issuance costs	20,825,383						$ 29,299			20,796,084
Issuance of common stock and warrants from the public and private offerings, net of issuance costs, shares							29,298,537
Net loss	(4,740,232)														(4,740,232)
Unrealized gain (loss) on short-term investments	(1,864)													(1,864)
Foreign currency translation adjustment	37,575													37,575
Balance at Sep. 30, 2019	28,116,504						$ 58,031			193,953,125				33,675	(165,928,327)
Balance, shares at Sep. 30, 2019							58,031,230
Balance at Dec. 31, 2019	23,969,634						$ 58,090			194,234,151				(4,964)	(170,317,643)
Balance, shares at Dec. 31, 2019							58,090,233
Stock-based compensation expense	415,256									415,256
Release of restricted stock awards	36						$ 36
Release of restricted stock awards, shares							35,942
Net share settlement of restricted stock award	(7,052)						$ (11)			(7,041)
Net share settlement of restricted stock award, shares							(11,266)
Employee stock purchase plan expense	5,379									5,379
Issuance of common stock			$ 2,435,912					$ 615	$ 4,399		$ (615)	$ 2,431,513
Issuance of common stock, shares								615,384	4,399,062
Issuance of preferred stock	2,424,900			$ 562,955	$ 41	$ 10				2,424,859			$ 562,945
Issuance of preferred stock, shares					41,100	10,170
Cancellation of common stock received in exchange for Series A convertible preferred stock	(2,424,900)						$ (4,110)			(2,420,790)
Cancellation of common stock received in exchange for Series A convertible preferred stock, shares							(4,110,000)
Exercise of pre-funded warrants	31,768						$ 3,177			28,591
Exercise of pre-funded warrants, shares							3,176,762
Adjustment in connection with LP Purchase Agreement commitment fee and transaction costs		$ (96,000)									(96,000)
Net loss	(5,457,898)														(5,457,898)
Unrealized gain (loss) on short-term investments	47,697													47,697
Foreign currency translation adjustment	5,497													5,497
Balance at Mar. 31, 2020	21,913,184				$ 51		$ 62,196			197,578,248				48,230	(175,775,541)
Balance, shares at Mar. 31, 2020					51,270		62,196,117
Balance at Dec. 31, 2019	23,969,634						$ 58,090			194,234,151				(4,964)	(170,317,643)
Balance, shares at Dec. 31, 2019							58,090,233
Issuance of common stock, shares									10,436,016
Net loss	(16,580,237)
Unrealized gain (loss) on short-term investments	4,060
Balance at Sep. 30, 2020	16,201,354				$ 24		$ 71,079			203,021,404				6,727	(186,897,880)
Balance, shares at Sep. 30, 2020					23,770		71,078,958
Balance at Mar. 31, 2020	21,913,184				$ 51		$ 62,196			197,578,248				48,230	(175,775,541)
Balance, shares at Mar. 31, 2020					51,270		62,196,117
Stock-based compensation expense	361,477									361,477
Release of restricted stock awards	24						$ 24
Release of restricted stock awards, shares							23,751
Net share settlement of restricted stock award	(2,108)						$ (7)			(2,101)
Net share settlement of restricted stock award, shares							(6,389)
Stock issued under stock purchase plans	30,512						$ 45			30,467
Stock issued under stock purchase plans, shares							45,490
Issuance of common stock			1,395,058						$ 2,085			1,392,973
Issuance of common stock, shares									2,084,714
Conversion of Series A convertible preferred stock for common stock					$ (27)		$ 2,750			(2,723)
Conversion of Series A convertible preferred stock for common stock, shares					(27,500)		2,750,000
Adjustment in connection with LP Purchase Agreement commitment fee and transaction costs		$ 301,538									$ 301,538
Issuance of common stock warrants in connection with SVB Term Loan	420,000									420,000
Net loss	(5,710,551)														(5,710,551)
Unrealized gain (loss) on short-term investments	(26,136)													(26,136)
Foreign currency translation adjustment	909													909
Balance at Jun. 30, 2020	18,683,907				$ 24		$ 67,093			200,079,879				23,003	(181,486,092)
Balance, shares at Jun. 30, 2020					23,770		67,093,683
Stock-based compensation expense	386,911									386,911
Release of restricted stock awards	38						$ 38
Release of restricted stock awards, shares							38,126
Net share settlement of restricted stock award	(3,664)						$ (4)			(3,660)
Net share settlement of restricted stock award, shares							(5,091)
Employee stock purchase plan expense	5,214									5,214
Issuance of common stock			$ 2,557,012						$ 3,952			$ 2,553,060
Issuance of common stock, shares									3,952,240
Net loss	(5,411,788)														(5,411,788)
Unrealized gain (loss) on short-term investments	(17,501)													(17,501)
Foreign currency translation adjustment	1,225													1,225
Balance at Sep. 30, 2020	$ 16,201,354				$ 24		$ 71,079			$ 203,021,404				$ 6,727	$ (186,897,880)
Balance, shares at Sep. 30, 2020					23,770		71,078,958