Note 9 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

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

	2016			2015			2014
Weighted average risk-free interest rates		2.26	%		1.99	%		1.98	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected life of option (yrs )	7.0			7.0			7.0
Expected volatility		88.72	%		91.43	%		94.88	%

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

	2016		2015		2014
General and administrative expense	$	31,191	$	45,822	$	69,057
Research and development expense		23,614		22,083		32,134
Total stock option expense	$	54,805	$	67,905	$	101,191

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

	2016		2015		2014
Weighted average fair value of options granted	$	0.05	$	0.09	$	0.14
Intrinsic value of options exercised		-0-		-0-		-0-
Total fair value of options vested		54,757		66,622		97,707