Note 2 - Stockholders' Equity (Deficit), Stock Options and Warrants (Details Textual) | Feb. 22, 2017USD ($) | Jan. 19, 2017USD ($)$ / sharesshares | Nov. 29, 2016USD ($)$ / sharesshares | Oct. 27, 2016 | Oct. 04, 2016$ / sharesshares | Jul. 01, 2016$ / sharesshares | Mar. 31, 2016shares | Aug. 31, 2015USD ($)$ / sharesshares | Jun. 30, 2015$ / sharesshares | Mar. 31, 2015$ / sharesshares | Feb. 04, 2014USD ($)$ / sharesshares | May 31, 2016shares | Jan. 31, 2015$ / sharesshares | Mar. 31, 2017USD ($)$ / sharesshares | Jul. 06, 2016shares | Mar. 31, 2016USD ($) | Sep. 30, 2016$ / sharesshares | Dec. 31, 2016USD ($)$ / sharesshares | Dec. 31, 2015$ / shares | Dec. 31, 2016USD ($)$ / sharesshares | Oct. 26, 2016shares | Sep. 15, 2016shares | Sep. 14, 2016shares | Apr. 21, 2016shares | Mar. 25, 2016$ / sharesshares |
Shares Issued, Price Per Share | $ / shares | | | | | | | | $ 9 | | | | | | | | | | | | | | | | | |
Underwriter Price | $ / shares | | | | | | | | 8.28 | | | | | | | | | | | | | | | | | |
Underwriting Discount | $ / shares | | | | | | | | $ 0.72 | | | | | | | | | | | | | | | | | |
Underwriting Commission | | | | | | | | 8.00% | | | | | | | | | | | | | | | | | |
Proceeds from Issuance or Sale of Equity | $ | | | | | | | | $ 13,800,000 | | | | | | | | | | | | | | | | | |
Option Granted to Underwriter to Purchase Additional Units Period | | | | | | | | 45 days | | | | | | | | | | | | | | | | | |
Option Granted to Underwriter to Purchase Additional Units Number of Units Granted | | | | | | | | 250,000 | | | | | | | | | | | | | | | | | |
Underwriting Agreement Non-accountable Expense Allowance Percentage | | | | | | | | 1.00% | | | | | | | | | | | | | | | | | |
Common Stock, Par or Stated Value Per Share | $ / shares | | | | | $ 0.01 | | | | | | | | | $ 0.01 | | | | $ 0.01 | | $ 0.01 | | | | | |
Share Price | $ / shares | | | | | | | | | | | | | | | | | $ 4.125 | | | | | | | | |
Class of Warrant or Right, Outstanding | | | | | | | | | | | | | | 1,256,101 | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | $ 3,421,188 | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | | 400,000 | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | | | | | | | | | | | | | | 0.00% | | | | 0.00% | 0.00% | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum | | | | | | | | | | | | | | 59.00% | | | | 59.00% | 59.00% | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum | | | | | | | | | | | | | | 66.00% | | | | 66.00% | 66.00% | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number | | | | | | | | | | | | | | 112,263 | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price | $ / shares | | | | | | | | | | | | | | $ 14.13 | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term | | | | | | | | | | | | | | 9 years 164 days | | | | | | | | | | | |
Class of Warrant or Right Number of Warrants Vested and Exercisable | | | | | | | | | | | | | | 499,102 | | | | | | | | | | | |
Allocated Share-based Compensation Expense | $ | | | | | | | | | | | | | | $ 99,307 | | $ 37,775 | | | | | | | | | |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options | $ | | | | | | | | | | | | | | $ 155,514 | | | | | | | | | | | |
Common Stock, Shares Authorized | | | | | | | | | | | | | | 24,000,000 | | | | 24,000,000 | | 24,000,000 | 8,000,000 | 200,000,000 | 100,000,000 | | |
Reverse Stock Split [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stockholders' Equity Note, Stock Split, Conversion Ratio | | | | 25 | | | | | | | | | | | | | | | | | | | | | |
Purchasers [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | | 125 | 125 | | | 125 | | | | | | | | | | | | |
Preferred Stock Conversion Price Per Share | $ / shares | | | | | | | | | | | | | $ 487.50 | | | | | | | | | | | | |
Conversion of Stock Price Per Share | $ / shares | | | | | | | | | $ 243.75 | $ 243.75 | | | $ 243.75 | | | | | | | | | | | | |
Number of Preferred Stock Share holders | | | | | | | | | 16 | 16 | | | 16 | | | | | | | | | | | | |
Preferred Stock, Dividend Rate, Percentage | | | | | | | | | 6.00% | 6.00% | | | | | | | | | | | | | | | |
Vice President of Sales [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Common Stock, Par or Stated Value Per Share | $ / shares | | | | | | $ 0.01 | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | | | | | $ 3.75 | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | | | | | | 40,000 | | | | | | | | | | | | | | | | | | | |
Number of Equal Installments Options are Expected to Vest | | | | | | 6 | | | | | | | | | | | | | | | | | | | |
The 2016 Registered Direct Offering [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Proceeds from Issuance or Sale of Equity | $ | | | $ 1,983,337 | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | | | $ 4.46 | | | | | | | | | | | | | | | | | | | | | | |
Share Price | $ / shares | | | $ 2.62 | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | | | | | $ 1,625,905 | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | 756,999 | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | | | 756,999 | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right Term | | | 5 years | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Vesting Period | | | 180 days | | | | | | | | | | | | | | | | | | | | | | |
Proceeds from Issuance or Sale of Equity, Net of Stock Issuance Costs | $ | | | $ 1,739,770 | | | | | | | | | | | | | | | | | $ 1,739,770 | | | | | |
The 2017 Public Offering [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Proceeds from Issuance or Sale of Equity | $ | | $ 3,937,500 | | | | | | | | | | | | | | | | | | | | | | | |
Share Price | $ / shares | | $ 2.25 | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | 1,750,000 | | | | | | | | | | | | | | | | | | | | | | | |
Share Per Each Unit | | 1 | | | | | | | | | | | | | | | | | | | | | | | |
Over-Allotment Option [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Proceeds from Issuance or Sale of Equity | $ | $ 358,312 | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | $ 393,750 | | | | | | | | | | | |
Sale of Stock, Underwriter Option Term | | 45 days | | | | | | | | | | | | | | | | | | | | | | | |
Sale of Stock, Underwriter Option, Maximum Additional Shares of Common Stock Available for Purchase | | 175,000 | | | | | | | | | | | | | | | | | | | | | | | |
Sale of Stock, Underwriter Option, Number of Securities Called by Maximum Additional Warrants Available for Purchase | | 35,000 | | | | | | | | | | | | | | | | | | | | | | | |
Sale of Stock, Underwriter Option, Exercise Price of Additional Warrants Available for Purchase | $ / shares | | $ 0.01 | | | | | | | | | | | | | | | | | | | | | | | |
The Convertible Notes [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Debt Instrument Redemption Principal Amount | $ | | | | | | | | $ 933,074 | | | | | | | | | | | | | | | | | |
Debt Instrument Redemption Premium Percentage | | | | | | | | 40.00% | | | | | | | | | | | | | | | | | |
Debt Instrument Redemption Price | $ | | | | | | | | $ 1,548,792 | | | | | | | | | | | | | | | | | |
Debt Instrument Redemption Amount Paid to Affiliates | $ | | | | | | | | $ 167,031 | | | | | | | | | | | | | | | | | |
Series B Convertible Preferred Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Beneficial Ownership Limitation Percentage | | | | | | | | 4.99% | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | $ 2,055,000 | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | | | | | | | | 20,550 | | | | | | | | | | | | | | |
Preferred Stock Par Value | $ / shares | | | | | | | | | | | $ 0.01 | | | | | | | | | | | | | | |
Preferred Stock Stated Value | $ / shares | | | | | | | | | | | $ 100 | | | | | | | | | | | | | | |
Series A Warrants [Member] | Exchange Offer [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock to be Issued for Exchange Offer, Shares, Maximum | | | | | | | | | | | | | | | | | | | | | | | | | 3,157,186 |
Cashless Exercise of Common Stock Warrants, Total | | | | | | | 10.05 | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | | | | | | | | | | | | | | | | | | | | | | | | 1,770,556 | |
Exchange from Series B Warrants to Warrant Shares [Member] | Exchange Offer [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Common Stock, Par or Stated Value Per Share | $ / shares | | | | | | | | | | | | | | | | | | | | | | | | | $ 0.01 |
Series B Warrants [Member] | Exchange Offer [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right Exercised During Period | | | | | | | | | | | | | | | 1,251,510 | | | | | | | | | | |
Stock Issued During Period Shares Warrants Exercised | | | | | | | | | | | | | | | 20,122 | | | | | | | | | | |
Cashless Exercise of Common Stock Warrants, Total | | | | | | | 10.2 | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | | | | | | | | | | | | | | | | | | | | | | | | 18,059,671 | |
Series D Warrants [Member] | The 2017 Public Offering [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right | | 1 | | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | | $ 2.25 | | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Issued per Unit | | 0.2 | | | | | | | | | | | | | | | | | | | | | | | |
Common Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period Shares Warrants Exercised | | | | | | | | | | | | | | | | | | 2,318,663 | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | $ 17,500 | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | | | | | | | | | | | 1,750,000 | | | | | | | | | | | |
Common Stock [Member] | The 2016 Registered Direct Offering [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | | | | | $ 7,570 | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | | | | | | | | | | | | | | | 756,999 | | | | | | | |
Common Stock [Member] | Over-Allotment Option [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Value, New Issues | $ | | | | | | | | | | | | | | $ 1,750 | | | | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | | | | | | | | | | | 175,000 | | | | | | | | | | | |
Common Stock [Member] | Series B Warrants [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period Shares Warrants Exercised | | | | | | | | | | | | | | | | | | 628,237 | | | | | | | |
Corporate Stock Transfer Inc. [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Unit Agreement Number of Shares of Common Stock Included in Each Unit | | | | | | | | 1 | | | | | | | | | | | | | | | | | |
Common Stock, Par or Stated Value Per Share | $ / shares | | | | | | | | $ 0.01 | | | | | | | | | | | | | | | | | |
Corporate Stock Transfer Inc. [Member] | Series A Warrants [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right | | | | | | | | 1 | | | | | | | | | 0.4 | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | | | | | | | | $ 123.75 | | | | | | | | | | | | | | | | | |
Cash Less Exercise Formula Definition of Letter C in the Formula Closing Bid Price Number of Trading Days Prior to the Time of Exercise | | | | | | | | 2 days | | | | | | | | | | | | | | | | | |
Cash Less Exercise Formula Closing Bid Price Per Share Minimum to Be Used in the Formula | $ / shares | | | | | | | | $ 0.43 | | | | | | | | | | | | | | | | | |
Warrants Option to Settle in Cash Fair Value Disclosure | $ / shares | | | | | | | | | | | | | | | | | $ 4.319 | | | | | | | | |
Class of Warrant or Right Exercised During Period | | | | | | | | | | | | | | | | | 6,141,115 | | | | | | | | |
Stock Issued During Period Shares Warrants Exercised | | | | | | | | | | | | | | | | | 2,318,663 | | | | | | | | |
Class of Warrant or Right, Outstanding | | | | | | | | 35,084 | | | | | | | | | | | | | | | | | |
Class of Warrant or Right Cash less Exercise Common Stock Price That Would Result in a Dilutive Exercise | $ / shares | | | | | | | | $ 0.43 | | | | | | | | | | | | | | | | | |
Beneficial Ownership Limitation Percentage | | | | | | | | 4.99% | | | | | | | | | | | | | | | | | |
Class of Warrant or Right Period Over Which Additional Adjustments to Price and Number of Shares May Be Made | | | | | | | | 3 years | | | | | | | | | | | | | | | | | |
Corporate Stock Transfer Inc. [Member] | Series A Warrants [Member] | Scenario, All Outstanding Warrants Exercised at Minimum Bid Price [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period Shares Warrants Exercised | | | | | | | | | | | | | | | | | 564 | | | | | | | | |
Corporate Stock Transfer Inc. [Member] | Series B Convertible Preferred Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Unit Agreement Number of Shares of Common Stock Included in Each Unit | | | | | | | | 1 | | | | | | | | | | | | | | | | | |
Corporate Stock Transfer Inc. [Member] | Series A Convertible Preferred Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Unit Agreement Number of Shares of Common Stock Included in Each Unit | | | | | | | | 4 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Unit Purchase Option Units Sold | | | | | | | | 1,666,667 | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | 1,895,010 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | Series A Convertible Preferred Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | 3,991 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | Series A Warrants [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | 7,580,040 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | Common Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | 75,801 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | Series B Convertible Preferred Stock [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | 1,895,010 | | | | | | | | | | | | | | | | | |
Exchange Units [Member] | Corporate Stock Transfer Inc. [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Unit Purchase Option Units Issued | | | | | | | | 228,343 | | | | | | | | | | | | | | | | | |
Stock Issued During Period, Shares, Conversion of Convertible Securities | | | | | | | | | | | | 135,995 | | | | | | | | | | | | | |
Unit Purchase Option Number of Units Available for Underwriter to Purchase, Percentage | | | | | | | | 5.00% | | | | | | | | | | | | | | | | | |
Unit Purchase Option Number of Units Available For Underwriter to Purchase | | | | | | | | 83,333 | | | | | | | | | | | | | | | | | |
Unit Purchase Option Exercise Price, Percentage | | | | | | | | 125.00% | | | | | | | | | | | | | | | | | |
Unit Purchase Option Exercise Price | $ / shares | | | | | | | | $ 11.25 | | | | | | | | | | | | | | | | | |
Maximum [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | | | | | | | | | | | | | | 3 years | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | | | | | | | | | | | | | 10 years | | | | | | | | | | | |
Underwriting Agreement Expenses Agreed to Reimburse the Underwriter | $ | | | | | | | | $ 70,000 | | | | | | | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | | | | | | | | | | | | | | $ 609.38 | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate | | | | | | | | | | | | | | 2.40% | | | | 2.45% | 2.35% | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | | | | | | | | | | | | | | | | | | | 10 years | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | | | | | | | | | | | | | $ 596.25 | | | | | $ 139.2375 | | | | | | |
Share-based Goods and Nonemployee Services Transaction, Valuation Method, Expected Term | | | | | | | | | | | | | | 10 years | | | | 10 years | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | | | | | | | | $ 1.5489 | | | | $ 3.7195 | | | | | | | |
Minimum [Member] | | | | | | | | | | | | | | | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period | | | | | | | | | | | | | | 3 years | | | | | | | | | | | |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares | | | | | | | | | | | | | | $ 0 | | | | | | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate | | | | | | | | | | | | | | 1.92% | | | | 1.46% | 1.63% | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | | | | | | | | | | | | | | 5 years | | | | 5 years | 5 years | | | | | | |
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price | $ / shares | | | | | | | | | | | | | | $ 2.10 | | | | | $ 6.875 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares | | | | | | | | | | | | | | $ 1.0293 | | | | $ 1.6329 | | | | | | | |