Liquidity and management's plans (Details Textual) - USD ($)				1 Months Ended		9 Months Ended
	Sep. 13, 2016	Jun. 27, 2016	Jul. 14, 2015	Jul. 31, 2015	May 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Conversion Of Stock [Line Items]
Common stock, par value (in dollars per share)						$ 0.01		$ 0.01
Proceeds from Issuance of Private Placement Net		$ 9,500,000				$ 9,460,751	$ 0
Proceeds from initial public offering, net of issuance costs					$ 17,100,000	$ 0	$ 12,408,285
Common Stock | Merck GHI [Member]
Conversion Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues			1,136,364	1,136,364
Proceeds From Issuance Of Shares And Debt				$ 6,000,000
Shares Issued, Price Per Share				$ 4.40
Common Stock | Promissory Note | Merck GHI [Member]
Conversion Of Stock [Line Items]
Debt Instrument, Face Amount				$ 1,000,000
Private Placement [Member]
Conversion Of Stock [Line Items]
Proceeds from Issuance of Private Placement Net		$ 9,500,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		6,790,169
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 1.14
Sale of Stock, Description of Transaction						(i) one share of common stock and a detachable stock purchase warrant to purchase an additional 0.75 shares of common stock, or (ii) one share of non-voting convertible preferred stock and a detachable stock purchase warrant to purchase an additional 0.75 shares of common stock, at a price of $1.14 per unit.
Private Placement [Member] | Non-voting Convertible Preferred Stock [Member]
Conversion Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		2,309,428
Private Placement [Member] | Common Stock
Conversion Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		6,744,127
Cowen and Company, LLC | Scenario, Plan | Sales Agreement [Member] | ATM Offering [Member]
Conversion Of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01
Stock Issued During period, Value, New Issues	$ 11,500,000
Cowen and Company, LLC | Scenario, Plan | Sales Agreement [Member] | Private Placement [Member]
Conversion Of Stock [Line Items]
Stock Issued During period, Value, New Issues	11,500,000
Remaining availability under ATM offering	11,500,000
Cowen and Company, LLC | Scenario, Plan | Maximum [Member] | Sales Agreement [Member] | ATM Offering [Member]
Conversion Of Stock [Line Items]
Aggregate Gross Proceeds From Issuance of Common Stock	$ 25,000,000