Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($)	Total	Public Offering [Member]	Series B Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Public Offering [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Public Offering [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2017	$ 39,395,823			$ 61		$ 121,657,587		$ (77,684,839)	$ (4,576,986)
Beginning Balance (in shares) at Dec. 31, 2017				608,499
Beginning Balance (in shares) at Dec. 31, 2017			12,177
Beginning Balance at Dec. 31, 2017			$ 9,281,767
Stock based compensation and vesting of restricted stock	356,737					356,737
Stock based compensation and vesting of restricted stock (in shares)				71
Exercises of stock options	18,488			$ 1		18,487
Exercises of stock options (in shares)				7,703
Accretion of Series B redeemable convertible preferred stock	(1,891,321)					(1,891,321)
Accretion of Series B redeemable convertible preferred stock			$ 1,891,321
Conversion of Series B convertible preferred stock into common stock	5,218,572			$ 13		5,218,559
Conversion of Series B convertible preferred stock into common stock (in shares)			(5,219)
Conversion of Series B convertible preferred stock into common stock			$ (5,218,572)
Conversion of Series B convertible preferred stock into common stock (in shares)				130,447
Foreign currency translation adjustments	615,471								615,471
Net loss	(3,173,538)							(3,173,538)
Ending Balance at Mar. 31, 2018	40,540,232			$ 75		125,360,049		(80,858,377)	(3,961,515)
Ending Balance (in shares) at Mar. 31, 2018				746,720
Ending Balance (in shares) at Mar. 31, 2018			6,958
Ending Balance at Mar. 31, 2018			$ 5,954,516
Beginning Balance at Dec. 31, 2017	39,395,823			$ 61		121,657,587		(77,684,839)	(4,576,986)
Beginning Balance (in shares) at Dec. 31, 2017				608,499
Beginning Balance (in shares) at Dec. 31, 2017			12,177
Beginning Balance at Dec. 31, 2017			$ 9,281,767
Foreign currency translation adjustments	(463,177)
Net loss	(14,663,529)
Ending Balance at Sep. 30, 2018	39,683,188			$ 173		137,071,546		(92,348,368)	(5,040,163)
Ending Balance (in shares) at Sep. 30, 2018				1,725,630
Beginning Balance at Mar. 31, 2018	40,540,232			$ 75		125,360,049		(80,858,377)	(3,961,515)
Beginning Balance (in shares) at Mar. 31, 2018				746,720
Beginning Balance (in shares) at Mar. 31, 2018			6,958
Beginning Balance at Mar. 31, 2018			$ 5,954,516
Stock based compensation and vesting of restricted stock	252,156					252,156
Stock based compensation and vesting of restricted stock (in shares)				71
Exercises of stock options	4,410					4,410
Exercises of stock options (in shares)				1,837
Accretion of Series B redeemable convertible preferred stock	(956,150)					(956,150)
Accretion of Series B redeemable convertible preferred stock			$ 956,150
Conversion of Series B convertible preferred stock into common stock	4,036,539			$ 33		4,036,506
Conversion of Series B convertible preferred stock into common stock (in shares)			(4,036)
Conversion of Series B convertible preferred stock into common stock			$ (4,036,539)
Conversion of Series B convertible preferred stock into common stock (in shares)				334,180
Redemption of Series B redeemable convertible preferred stock for cash and release of embedded derivative	23,292					23,292
Redemption of Series B redeemable convertible preferred stock for cash and release of embedded derivative (in shares)			(2,364)
Redemption of Series B redeemable convertible preferred stock for cash and release of embedded derivative			$ (2,364,044)
Issuance of common stock for the exchange of warrants	2,127,000			$ 17		2,126,983
Issuance of common stock for the exchange of warrants (in shares)				167,700
Foreign currency translation adjustments	(1,078,648)								(1,078,648)
Net loss	(9,138,842)							(9,138,842)
Ending Balance at Jun. 30, 2018	35,809,989			$ 125		130,847,246		(89,997,219)	(5,040,163)
Ending Balance (in shares) at Jun. 30, 2018				1,250,508
Ending Balance (in shares) at Jun. 30, 2018			558
Ending Balance at Jun. 30, 2018			$ 510,083
Stock based compensation and vesting of restricted stock	95,649					95,649
Stock based compensation and vesting of restricted stock (in shares)				71
Accretion of Series B redeemable convertible preferred stock	(47,414)					(47,414)
Accretion of Series B redeemable convertible preferred stock			$ 47,414
Conversion of Series B convertible preferred stock into common stock	535,257			$ 4		535,253
Conversion of Series B convertible preferred stock into common stock (in shares)			(558)
Conversion of Series B convertible preferred stock into common stock			$ (557,497)
Conversion of Series B convertible preferred stock into common stock (in shares)				37,451
Issuance of common stock and units, net of offerings cost		$ 4,334,815			$ 29		$ 4,334,786
Issuance of common stock in registered direct offering, net of offering costs (in shares)					286,633
Issuance of common stock for the exchange of warrants	1,306,041			$ 15		1,306,026
Issuance of common stock upon exercise of warrants (in shares)				150,968
Net loss	(2,351,149)							(2,351,149)
Ending Balance at Sep. 30, 2018	39,683,188			$ 173		137,071,546		(92,348,368)	(5,040,163)
Ending Balance (in shares) at Sep. 30, 2018				1,725,630
Beginning Balance at Dec. 31, 2018	48,312,566			$ 876		170,207,844		(116,855,991)	(5,040,163)
Beginning Balance (in shares) at Dec. 31, 2018				9,078,238
Stock based compensation and vesting of restricted stock	407,742					407,742
Stock based compensation and vesting of restricted stock (in shares)				71
Issuance of common stock and units, net of offerings cost		$ 12,668,784			$ 436		$ 12,668,348
Issuance of common stock in registered direct offering, net of offering costs (in shares)					4,361,370
Issuance of common stock upon exercise of warrants	30,324			$ 1		30,323
Issuance of common stock upon exercise of warrants (in shares)				11,000
Net loss	(2,097,306)							(2,097,306)
Ending Balance at Mar. 31, 2019	59,322,110			$ 1,313		183,314,257		(118,953,297)	(5,040,163)
Ending Balance (in shares) at Mar. 31, 2019				13,450,679
Beginning Balance at Dec. 31, 2018	48,312,566			$ 876		170,207,844		(116,855,991)	(5,040,163)
Beginning Balance (in shares) at Dec. 31, 2018				9,078,238
Unrealized gain on short-term investments	18,953
Net loss	(16,423,506)
Ending Balance at Sep. 30, 2019	49,383,950			$ 1,502		187,683,155		(133,279,497)	(5,021,210)
Ending Balance (in shares) at Sep. 30, 2019				15,338,072
Beginning Balance at Mar. 31, 2019	59,322,110			$ 1,313		183,314,257		(118,953,297)	(5,040,163)
Beginning Balance (in shares) at Mar. 31, 2019				13,450,679
Stock based compensation and vesting of restricted stock	289,800					289,800
Stock based compensation and vesting of restricted stock (in shares)				71
Net loss	(3,386,888)							(3,386,888)
Ending Balance at Jun. 30, 2019	56,225,022			$ 1,313		183,604,057		(122,340,185)	(5,040,163)
Ending Balance (in shares) at Jun. 30, 2019				13,450,750
Stock based compensation and vesting of restricted stock	287,802					287,802
Stock based compensation and vesting of restricted stock (in shares)				72
Issuance of common stock for acquired in-process research and development	3,791,485			$ 189		3,791,296
Issuance of common stock for acquired in-process research and development (in shares)				1,887,250
Unrealized gain on short-term investments	18,953								18,953
Net loss	(10,939,312)							(10,939,312)
Ending Balance at Sep. 30, 2019	$ 49,383,950			$ 1,502		$ 187,683,155		$ (133,279,497)	$ (5,021,210)
Ending Balance (in shares) at Sep. 30, 2019				15,338,072