Note 6 - Warrants (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

							Weighted
							a verage		Aggregate
	Warrants		Exercise				p rice per		intrinsic
As of March 31, 2018 :	o utstanding		p rice per share				share		value (1)
Balance, December 31, 2017		22,104,817		$0.125	–	1.00	$	0.45
Issued		2,611,513		0.25	–	0.48		0.35
Balance, March 31, 2018		24,716,330		$0.125	–	1.00	$	0.44	$	—
As of March 31, 2019 :
Balance, December 31, 2018		26,872,430		$0.25	–	1.00	$	0.42
Issued		3,861,041		$0.16	–	0.25	$	0.24
Balance, March 31, 2019		30,733,471		$0.20	–	1.00	$	0.40	$	—

Schedule Of Assumptions Used To Determine Fair Value Of Warrants [Table Text Block]

	March 31, 2018				March 31, 2019
Risk free interest rate			2.54%			2.18	–	2.62%
Expected volatility			252%			86	–	110%
Expected dividend yield			—				—
Forfeiture rate			—				—
Expected life in years		5	–	10		2	–	5