Note 17 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Tax at federal statutory rate	$ (3,505,000)	$ (2,277,000)
State, net of federal benefit	(315,000)	(335,000)
Research and development credit	(89,000)	(51,000)
Stock-based compensation	136,000	89,000
Nondeductible interest	590,000	471,000
Warrant and derivative revaluation	328,000	(589,000)
Merger cost	90,000
Other	4,000	5,000
Increase in valuation allowance	2,761,000	2,687,000
Total provision for income taxes	$ 0	$ 0