Note 5 - Stockholders' Equity - Options Issued Outside of 2007 Plan (Details) - Outside of the 2007 Plan [Member] - $ / shares	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Minimum [Member]
Label Balances, exercise price per share (in dollars per share)	$ 0.18	$ 0.18
Granted, exercise price per share (in dollars per share)	0.33	0.34
Plan classification, exercise price per share (in dollars per share)		0.30
Balance, exercise price per share (in dollars per share)	0.18	0.18
Maximum [Member]
Label Balances, exercise price per share (in dollars per share)	1
Balances, weighted average price per share (in dollars per share)		1
Granted, exercise price per share (in dollars per share)	0.76
Granted, weighted average price per share (in dollars per share)		0.36
Plan classification, exercise price per share (in dollars per share)		0.63
Balance, exercise price per share (in dollars per share)	$ 1	$ 1
Balances, options outstanding (in shares)	19,394,975	17,965,291
Balances, weighted average price per share (in dollars per share)	$ 0.40	$ 0.40
Granted, options outstanding (in shares)	906,973	1,893,434
Granted, weighted average price per share (in dollars per share)	$ 0.48	$ 0.35
Expired, options outstanding (in shares)		(46,250)
Expired, exercise price per share (in dollars per share)		$ 0.30
Expired, weighted average price per share (in dollars per share)		$ 0.30
Plan classification, shares available (in shares)		(600,000)
Plan classification, exercise price per share (in dollars per share)		$ 0.33
Balance, options outstanding (in shares)	20,241,948	19,212,474
Balances, weighted average price per share (in dollars per share)	$ 0.41	$ 0.44
Exercised, options outstanding (in shares)	(60,000)
Exercised, exercise price per share (in dollars per share)	$ 0.25
Exercised, weighted average price per share (in dollars per share)	$ 0.25