Share-based payments (Details 1)	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Number of Warrants
Shares Outstanding, Beginning | shares	14,467,717
Granted | shares
Forfeited or expired | shares	(6,571,901)
Shares Outstanding, Ending | shares	45,795,986
Shares Exercisable, Ending | shares	45,795,986
Weighted Average Exercise Price
Per share Outstanding, Beginning | $ / shares	$ 0.18
Granted | $ / shares
Forfeited or expired | $ / shares	0.56
Outstanding, Ending | $ / shares	0.12
Per share Exercisable, Ending | $ / shares	$ 0.12
Weighted-average Remaining Life (Years)
Outstanding, Beginning	1 year 3 months 19 days
Outstanding, Ending	1 year 7 months 6 days
Exercisable, Ending	1 year 7 months 6 days
Nonemployee common stock warrants - Fully-vested upon issuance [Member]
Number of Warrants
Shares Outstanding, Beginning | shares	13,445,836
Granted | shares	1,300,000
Forfeited or expired | shares	(5,510,000)
Shares Outstanding, Ending | shares	9,235,836
Shares Exercisable, Ending | shares	9,235,836
Weighted Average Exercise Price
Per share Outstanding, Beginning | $ / shares	$ 0.27
Granted | $ / shares	0.05
Forfeited or expired | $ / shares	0.51
Outstanding, Ending | $ / shares	0.10
Per share Exercisable, Ending | $ / shares	$ 0.10
Weighted-average Remaining Life (Years)
Outstanding, Beginning	1 year 4 months 24 days
Outstanding, Ending	1 year 8 months 12 days
Exercisable, Ending	1 year 8 months 12 days
Aggregate Intrinsic Value
Outstanding, Beginning | $	$ 78,000
Outstanding, Ending | $	194,500
Exercisable | $	$ 194,500