Note 9 - Fair Value Measurement - Change in Level 3 Financial Liabilities Fair Value (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance, beginning of year	$ (6,325,092)	$ (2,816,166)
Net realized gains/(losses)	48,375	29,108
Net unrealized gains/(losses) relating to instruments still held at the reporting date	747,404	(2,687,018)
Net purchases, issuances and settlements	0	(851,016)
Net transfers in and/or out of Level 3	402,567	0
Balance, end of period	(5,126,746)	(6,325,092)
Conversion Feature Liability [Member]
Balance, beginning of year	(2,325,730)	(901,243)
Net realized gains/(losses)	48,375	29,108
Net unrealized gains/(losses) relating to instruments still held at the reporting date	188,841	(1,453,595)
Net purchases, issuances and settlements	0	0
Net transfers in and/or out of Level 3	402,567	0
Balance, end of period	(1,685,947)	(2,325,730)
Warrant Liability [Member]
Balance, beginning of year	(3,999,362)	(1,914,923)
Net realized gains/(losses)	0	0
Net unrealized gains/(losses) relating to instruments still held at the reporting date	558,563	(1,233,423)
Net purchases, issuances and settlements	0	(851,016)
Net transfers in and/or out of Level 3	0	0
Balance, end of period	$ (3,440,799)	$ (3,999,362)