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 9 Months Ended 12 Months Ended
Sep. 28, 2018
Jun. 29, 2018
May 30, 2018
Mar. 29, 2018
Dec. 06, 2017
Jul. 31, 2018
Jun. 30, 2018
Apr. 30, 2018
Jan. 31, 2018
Sep. 30, 2018
Sep. 28, 2018
Jun. 30, 2018
Sep. 30, 2017
Jun. 30, 2018
Sep. 30, 2018
Sep. 28, 2018
Sep. 30, 2017
Dec. 31, 2017
Dec. 05, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance                   4,298,565         4,298,565     2,694,224  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance                   $ 4.64         $ 4.64     $ 5.80  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                             8 years 182 days     8 years 219 days  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross                             2,271,059        
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                                 $ 31,000    
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                   $ 5,604,000         $ 5,604,000        
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition                             2 years 317 days        
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                   60,000         60,000        
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, Equity Instruments Other than Options, Vested in Period             0               25,000        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period             2 years   1 year                    
The 2006 Stock Option Plan [Member]                                      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance                   38,378         38,378        
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant                   0         0        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance                   $ 10.49         $ 10.49        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                             4 years 36 days        
The 2013 Plan [Member]                                      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance                   4,260,187         4,260,187        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance                   $ 4.59         $ 4.59        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term                             8 years 182 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                   378,615         378,615        
The 2013 Plan [Member] | Employees [Member]                                      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross                   237,500     305,000   2,058,671   720,110    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value                   $ 3.01     $ 3.91   $ 3.65   $ 2.83    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period                   0         0   7,730    
The 2013 Plan [Member] | Nonemployees [Member]                                      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross                   10,000     14,000   212,388   19,875    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value                   $ 2.83     $ 3.66   $ 2.42   $ 4.09    
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           18,278   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           $ 2.63   $ 3.44 $ 5.19                    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period           18,278   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                     $ 0.75         $ 1      
Stock Issued During Period, Shares, Employee Stock Purchase Plans 28,698 25,618   20,744                              
Employee Stock Purchase Plan, Purchase Price $ 2.24 $ 2.31   $ 3.11             $ 2.24         $ 2.24      
Employee Stock Ownership Plan (ESOP), Number of Suspense Shares                   307,046         307,046        
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate                       0.00%   0.00%