8. Share-based payments (Details 5) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Number of Warrants
Outstanding, Beginning	14,421,379	14,421,379
Granted	14,400,000
Outstanding, Ending	14,467,717	14,421,379
Exercisable, Ending	14,467,717	14,421,379
Weighted Average Exercise Price
Outstanding, Beginning	$ 0.02	$ 0.02
Granted	0.05
Forfeited or expired	0.16
Outstanding, Ending	0.05	0.02
Exercisable, Ending	$ 0.05	$ 0.02
Weighted-average Remaining Life (Years)
Outstanding	1 year 6 months	2 years 6 months
Exercisable	4 years 7 months 6 days	1 year 6 months
Aggregate Intrinsic Value
Exercisable, Ending	$ 1,564	$ 725,950
Nonemployee Common stock warrants - Service and performance conditions [Member]
Number of Warrants
Outstanding, Beginning	3,280,000	3,400,000
Granted
Forfeited or expired	(2,120,000)	(120,000)
Outstanding, Ending	1,160,000	3,280,000
Exercisable, Ending	1,160,000	1,280,000
Weighted Average Exercise Price
Outstanding, Beginning	$ 0.83	$ 0.84
Granted
Forfeited or expired	1.00	1.00
Outstanding, Ending	0.52	0.83
Exercisable, Ending	$ 0.52	$ 0.56
Weighted-average Remaining Life (Years)
Outstanding	4 months 24 days	3 months 19 days
Forfeited or expired	0 years
Exercisable	4 months 24 days	8 months 12 days
Aggregate Intrinsic Value
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Weighted average remaining contractual term for equity-based awards excluding options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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