Note 9 - Fair Value Measurement - Fair Value of Liabilities Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Derivative Liability fair value	[1],[2]	$ 1,995,238	$ 5,126,746
Fair Value, Inputs, Level 1 [Member]
Derivative Liability fair value	[1],[2]	0	0
Fair Value, Inputs, Level 2 [Member]
Derivative Liability fair value	[1],[2]	0	0
Fair Value, Inputs, Level 3 [Member]
Derivative Liability fair value	[1],[2]	1,995,238	5,126,746
Conversion Feature Liability [Member]
Derivative Liability fair value	[1],[2]	706,339	1,685,947
Conversion Feature Liability [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Liability fair value	[1],[2]	0	0
Conversion Feature Liability [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Liability fair value	[1],[2]	0	0
Conversion Feature Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Liability fair value	[1],[2]	706,339	1,685,947
Warrant Liability [Member]
Derivative Liability fair value	[1],[2]	1,288,899	3,440,799
Warrant Liability [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative Liability fair value	[1],[2]	0	0
Warrant Liability [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative Liability fair value	[1],[2]	0	0
Warrant Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative Liability fair value	[1],[2]	$ 1,288,899	$ 3,440,799

[1] The fair value at the measurement date is equal to the carrying value on the balance sheet.

[2] The fair value of the derivative instruments was estimated using the Income Approach and the Black Scholes option pricing model with the following assumptions for the year ended December 31, 2018.