Note 13 - Subsequent Events (Details Textual) - USD ($)						1 Months Ended			3 Months Ended	12 Months Ended
	Mar. 26, 2019	Mar. 12, 2019	Mar. 01, 2019	Feb. 06, 2019	Jan. 08, 2019	Dec. 31, 2018	Nov. 30, 2018	Jan. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Jul. 11, 2018	Jul. 10, 2018
Shares Issued, Price Per Share											$ 1.17	$ 1.18
Debt Instrument, Penalty Expenses										$ 503,000
Chief Executive Officer [Member]
Proceeds from Related Party Debt						$ 370,000	$ 370,000
The 2018 Public Offering [Member]
Stock Issued During Period, Shares, New Issues								2,900,000
Share Per Each Unit								1
Proceeds from Issuance or Sale of Equity, Total								$ 2,755,000
Subsequent Event [Member] | Chief Executive Officer [Member]
Stock Issued During Period, Shares, New Issues					78,125
Shares Issued, Price Per Share					$ 0.64
Proceeds from Related Party Debt		$ 1,300,000		$ 300,000	$ 950,000				$ 1,300,000
Subsequent Event [Member] | Peak One [Member] | Bridge Loan [Member]
Debt Conversion, Converted Instrument, Shares Issued		71,046
Debt Conversion, Original Debt, Amount		$ 44,475
Subsequent Event [Member] | Right to Purchase Units [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			69,250
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 1.125
Right to Purchase Units, Percentage			5.00%
Right to Purchase Units, Exercise Price Percentage			125.00%
Subsequent Event [Member] | The 2019 Offering [Member]
Stock Issued During Period, Shares, New Issues			1,385,000
Share Per Each Unit			1
Shares Issued, Price Per Share			$ 0.90
Proceeds from Issuance or Sale of Equity, Total			$ 1,250,000
Proceeds from Issuance or Sale of Equity, Net of Stock Issuance Costs			$ 1,080,000
Underwriter Discount Percentage			8.00%
Placement Agent Offering Fees			$ 30,000
Placement Agent Blue Sky Fees			$ 5,000
Subsequent Event [Member] | The 2019 Offering [Member] | The 2019 Offering Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			692,500
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			0.5
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 1
Subsequent Event [Member] | The 2018 Public Offering [Member] | The 2019 Offering Warrants [Member]
Warrants and Rights Outstanding, Term			5 years
Subsequent Event [Member] | Placement Agency Agreement [Member]
Stock Issued During Period, Shares, New Issues	1,478,750
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	73,938
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1
Shares Issued, Price Per Share	$ 0.80
Proceeds from Issuance or Sale of Equity, Total	$ 1,180,000
Proceeds from Issuance or Sale of Equity, Net of Stock Issuance Costs	1,050,000
Placement Agent Offering Fees	30,000
Placement Agent Blue Sky Fees	$ 5,000
Right to Purchase Units, Percentage	5.00%
Right to Purchase Units, Exercise Price Percentage	125.00%
Unit Agreement Number of Shares of Common Stock Included in Each Unit	1
Unit Agreement Number of Warrants Included in Each Unit	0.5
Placement Fee, Percent of Gross Proceeds	8.00%
Subsequent Event [Member] | Placement Agency Agreement [Member] | Warrants Issued With Placement Agency Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	739,375
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 1