Note 4 - Share-based Compensation (Details Textual) - USD ($) $ / shares in Units, xbrli-pure in Thousands							3 Months Ended		6 Months Ended
	Jun. 19, 2017	May 02, 2017	Apr. 30, 2017	Feb. 10, 2017	Jun. 20, 2016	Mar. 21, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 30, 2016	Dec. 27, 2016	Sep. 17, 2016
Share Price											$ 0.83	$ 0.86	$ 0.70
Employee Stock Option [Member]
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Expected Forfeiture Rate									0.00%
The 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price									$ 0.65	$ 0.45
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross									340,000	40,000
Outside of the 2007 Plan [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price									$ 0.47	$ 0.38
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross									4,552,201	484,077
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value							$ 20,025	$ 75,405	$ 40,050	$ 170,310
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period									3,866,629
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense							235,671	$ 189,601	$ 515,959	$ 491,440
Selling, General and Administrative Expenses [Member] | The 2007 Equity Incentive Plan [Member]
Allocated Share-based Compensation Expense						$ 119,971
President and Chief Executive Officer [Member]
Employment Agreement, Common Stock, Expect to Grant, Subject to Lock-Up Agreement		1,500,000
Employment Agreement, Option, Number of Shares, Expected to Grant		3,731,322
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Employment Agreement, Term		5 years
Employment Agreement, Lock-up Agreement, Successful Commercialization, Minimum Cash Receipt		$ 3,000,000
Employment Agreement, Lock-up Agreement, Minimum Revenue Recognized		$ 3,000,000
President and Chief Executive Officer [Member] | Non-Qualified Stock Option [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price		$ 0.45
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Sharebased Compensation Arrangement by Sharebased Payment Award Options Granted in Period, Fair Value		$ 1,679,095
President and Chief Executive Officer [Member] | 2007 Stock Option [Member]
Investment Options, Exercise Price			$ 0.18
Stock Issued During Period, Shares, New Issues			3,866,630
Share Price			$ 0.51
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period			3,866,629
President and Chief Executive Officer [Member] | Shares Issued for the Exercise of 2007 Stock Option [Member]
Stock Issued During Period, Shares, New Issues			2,501,937
President and Chief Executive Officer [Member] | Selling, General and Administrative Expenses [Member] | Non-Qualified Stock Option [Member]
Allocated Share-based Compensation Expense							27,985
Non-employee Members of the Board of Directors [Member] | The 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0.43				$ 0.45
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	40,000				40,000
Non-employee Members of the Board of Directors [Member] | Selling, General and Administrative Expenses [Member] | The 2007 Equity Incentive Plan [Member]
Sharebased Compensation Arrangement by Sharebased Payment Award Options Granted in Period, Fair Value					$ 18,000
Allocated Share-based Compensation Expense	$ 15,600
Chief Financial Officer [Member] | The 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price				$ 0.69
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares				125,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Remaining Number of Shares to Vest Each Month				25,000
Sharebased Compensation Arrangement by Sharebased Payment Award Options Granted in Period, Fair Value							207,000		207,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross				300,000
Chief Financial Officer [Member] | Selling, General and Administrative Expenses [Member] | The 2007 Equity Incentive Plan [Member]
Allocated Share-based Compensation Expense							$ 51,750		$ 155,250
Board of Directors and Vendors [Member] | The 2007 Equity Incentive Plan [Member]
Sharebased Compensation Arrangement By Sharebased Payment Award Options Expiration Period Extension						5 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross						307,777
Board of Directors and Vendors [Member] | Outside of the 2007 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross							237,353	220,554	820,879	484,077
Board of Directors and Vendors [Member] | Outside of the 2007 Plan [Member] | Minimum [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price									$ 0.43	$ 0.33
Board of Directors and Vendors [Member] | Outside of the 2007 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price									$ 0.67	$ 0.45
Board of Directors and Vendors [Member] | Selling, General and Administrative Expenses [Member] | Outside of the 2007 Plan [Member]
Allocated Share-based Compensation Expense							$ 120,311	$ 96,196	$ 277,074	$ 183,159