License agreements, research collaborations and development agreements (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) Agreement	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Agreement	Jun. 30, 2016 USD ($)
License Agreements Research Collaborations And Development Agreements [Line Items]
Royalty expense	$ 62,941	$ 75,948	$ 132,186	$ 145,802
Annual future minimum royalty payments due	250,000		250,000
Collaborations revenue	6,233	$ 125,000	27,397	$ 125,000
License Agreement with Hitachi [Member]
License Agreements Research Collaborations And Development Agreements [Line Items]
Collaborations revenue	$ 6,233		$ 12,397
FISH Product Line [Member]
License Agreements Research Collaborations And Development Agreements [Line Items]
Number of license agreements | Agreement	1		1