Note 6 - Warrants (Details Textual) - USD ($)			3 Months Ended					9 Months Ended
	Sep. 26, 2017	May 24, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jul. 18, 2017	Dec. 30, 2016	Dec. 27, 2016	Sep. 17, 2016	Jul. 08, 2016	Dec. 31, 2015
Class of Warrant or Right, Issued During Period								2,499,933	5,670,996
Debt Instrument, Convertible, Conversion Price													$ 0.55
Class of Warrant or Right, Outstanding			21,775,047			20,035,114	18,036,889	21,775,047	18,036,889						13,779,438
Share Price											$ 0.83	$ 0.86	$ 0.70
Debt Conversion, Original Debt, Amount								$ 354,326	$ 272,032
Stock Issued During Period, Shares, Exercise of Warrants							1,150,000	510,000
Proceeds from Warrant Exercises							$ 355,000	$ 153,000	$ 355,000
Summer 2017 Unit Offering [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights											$ 0.42
Debt Instrument, Convertible, Conversion Price		$ 0.42
Warrants Issued Concurrently to the Summer 2017 Unit Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,169,525					1,169,525
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.65
Class of Warrant or Right, Issued During Period		219,048	931,429	238,096
Class of Warrant or Right, Outstanding		619,048
Warrants Issued Concurrently With One Year Convertible Note [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	577,777									400,000	400,000			400,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 0.42	$ 0.42								$ 0.65	$ 0.75			$ 0.65
Discount On Convertible Note Payable			$ 280,000					$ 280,000			$ 280,000			$ 160,000
Class of Warrant or Right, Increase (Decrease) in Securities Called by Warrants or Rights	177,777
Warrants Issued Concurrently to the Summer 2017 Unit Offering 2 [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.42
Class of Warrant or Right, Issued During Period		314,285
Class of Warrant or Right, Outstanding		714,285
Series A Warrant [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							4,455,413		4,455,413
Discount On Convertible Note Payable							$ 1,940,000		$ 1,940,000
Series A Warrants, Exercise Price 1 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							2,719,048		2,719,048
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 0.45		$ 0.45
Series A Warrants, Exercise Price 2 [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,736,365		1,736,365
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 0.70		$ 0.70
Warrants Issued Concurrently with Line of Credit [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							300,000		300,000
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 0.35		$ 0.35
Debt Instrument, Unamortized Discount							$ 237,405		$ 237,405
Warrant Issued in Exchange of Cancelled Line of Credit [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights													515,583
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 0.70		$ 0.70				$ 0.70
Discount On Convertible Note Payable							$ 283,571		$ 283,571
Debt Conversion, Original Debt, Amount									$ 515,583
Warrants Issued Concurrently to the Summer 2017 Unit Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,169,525					1,169,525
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.65					$ 0.65
Warrants Issued Concurrently with Winter 2016 Unit Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					512,281
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 0.70
Class of Warrant or Right, Issued During Period					219,298	292,983
Discount On Convertible Note Payable			$ 491,200		$ 125,000			$ 491,200