Quarterly report pursuant to Section 13 or 15(d)

Note 12 - Stockholders' Equity (Details Textual)

v3.23.3
Note 12 - Stockholders' Equity (Details Textual)
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Aug. 31, 2023
USD ($)
$ / shares
shares
Jul. 31, 2023
USD ($)
$ / shares
shares
Sep. 30, 2023
USD ($)
shares
Jun. 30, 2023
USD ($)
shares
Mar. 31, 2023
USD ($)
shares
Sep. 30, 2022
shares
Sep. 30, 2023
USD ($)
shares
Sep. 30, 2022
USD ($)
shares
Dec. 31, 2019
shares
Dec. 31, 2022
shares
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)             939,198      
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation | $             $ 1,091,000      
Proceeds from Issuance of Common Stock | $             $ 3,788,000 $ 5,622,000    
Stock Issued During Period, Shares, Issued for Class Action Settlement (in shares)             469,366      
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)             192,707      
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)     0     0 0 0    
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)     5,907,653       5,907,653     5,262,254
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number (in shares)     113,195       113,195     994,267
The 2014 Stock Incentive Plan [Member]                    
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)     522,020       522,020      
The 2019 Stock Incentive Plan [Member]                    
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)     5,385,633       5,385,633      
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)                 18,500,000  
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)                 10 years  
Public Offering Warrant [Member]                    
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)   363,860                
Sale of Stock, Warrants, Commission Percent   2.00%                
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares   $ 1.375                
Warrants and Rights Outstanding, Term (Year)   5 years                
Yulho SPA Underwriter Warrant [Member]                    
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 205,761                  
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares $ 1.25                  
Warrants and Rights Outstanding, Term (Year) 5 years                  
ATM [Member]                    
Stock Issued During Period, Shares, New Issues (in shares)             3,244,302      
Proceeds from Issuance of Common Stock | $             $ 3.8      
July 2023 Public Offering [Member]                    
Stock Issued During Period, Shares, New Issues (in shares)   18,193,000                
Proceeds from Issuance of Common Stock | $   $ 18,300,000                
Yulho Offering [Member]                    
Stock Issued During Period, Shares, New Issues (in shares) 4,545,455                  
Proceeds from Issuance of Common Stock | $ $ 4,600,000                  
Options Granted in Reliance on Nasdaq Rule 5635(c)(4) [Member]                    
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number (in shares)     840,000       840,000      
Restricted Stock Units (RSUs) [Member]                    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)     136,254 204,547 64,149   489,569      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Fair Value | $     $ 155,000 $ 225,000 $ 70,000          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Number of Installments     3 4 3          
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)     3 years 12 months 3 years          
Management and Employees [Member]                    
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)             1,413,886      
Management and Employees [Member] | Reissued Treasury Stock [Member]                    
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)             510,632      
Board Members [Member]                    
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)             130,918      
Former Board Member [Member]                    
Stock Issued During Period, Shares, Issued for Services (in shares)             15,781      
Director [Member]                    
Stock Issued During Period, Shares, Issued for Services (in shares)             84,619