Note 9 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	201 7			201 6			20 15
Weighted average risk-free interest rates		2.40	%		2.26	%		1.99	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected life of option (yrs)	7.0			7.0			7.0
Expected volatility		89.73	%		88.72	%		91.43	%

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	201 7		201 6		20 15
General and administrative expense	$	31,271	$	31,191	$	45,822
Research and development expense		25,953		23,614		22,083
Total stock option expense	$	57,224	$	54,805	$	67,905

Share-based Compensation, Stock Options, Activity [Table Text Block]

	201 7		201 6		201 5
Weighted average fair value of options granted	$	0.04	$	0.05	$	0.09
Intrinsic value of options exercised		-		-		-
Total fair value of options vested		58,337		54,757		66,622