Quarterly report pursuant to Section 13 or 15(d)

Note 9 - Summary of Stock Options (Details Textual)

v3.10.0.1
Note 9 - Summary of Stock Options (Details Textual) - USD ($)
1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 29, 2018
May 30, 2018
Mar. 29, 2018
Dec. 06, 2017
Jun. 30, 2018
Apr. 30, 2018
Jan. 31, 2018
Jun. 30, 2018
Mar. 31, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Dec. 05, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance         4,209,355     4,209,355     4,209,355   2,694,224  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance         $ 4.76     $ 4.76     $ 4.76   $ 5.80  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                     8 years 292 days   8 years 219 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross                     2,023,559      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period                          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value                       $ 30,785    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate               0.00%   0.00% 0.00% 0.00%    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options         $ 6,341,000     $ 6,341,000     $ 6,341,000      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition                     3 years      
Nonemployees [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate               0.00%   0.00% 0.00% 0.00%    
Employee Stock Option [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost   $ 97,000                        
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate                     0.00%      
Restricted Stock [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance         66,250     66,250     66,250      
Restricted Stock [Member] | Consultant [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period         50,000   25,000              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value         $ 3.58   $ 5.19              
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period         2 years   1 year              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period         0           18,750      
The 2006 Stock Option Plan [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance         38,378     38,378     38,378      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant         0     0     0      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance         $ 10.49     $ 10.49     $ 10.49      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                     4 years 146 days      
The 2013 Plan [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance         4,170,977     4,170,977     4,170,977      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance         $ 4.71     $ 4.71     $ 4.71      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                     8 years 292 days      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized       914,016                    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized       4,914,016                   4,000,000
Common Stock, Capital Shares Reserved for Future Issuance         486,103     486,103     486,103      
The 2013 Plan [Member] | Employees [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross               570,000   185,250 1,821,171 415,110    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value               $ 1.34   $ 3.31 $ 2.32 $ 2.56    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period               0   7,730 0 7,730    
The 2013 Plan [Member] | Nonemployees [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross               200,000   5,875 202,388 5,875    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value               $ 1.59   $ 5.11 $ 1.61 $ 5.11    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period               0   0 0 0    
The 2013 Plan [Member] | Restricted Stock [Member] | Board Members [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period           14,672     9,637          
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value           $ 3.44 $ 5.19              
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period           14,672 9,637              
2017 Employee Stock Purchase Plan [Member]                            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value               $ 0.95     $ 1.11      
Stock Issued During Period, Shares, Employee Stock Purchase Plans 25,618   20,744                      
Employee Stock Purchase Plan, Purchase Price $ 2.31   $ 3.11                      
Employee Stock Ownership Plan (ESOP), Number of Suspense Shares         335,744     335,744     335,744      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate               0.00%     0.00%