Quarterly report pursuant to Section 13 or 15(d)

Note 2 - Summary of Significant Accounting Policies (Details Textual)

v3.21.2
Note 2 - Summary of Significant Accounting Policies (Details Textual)
 3 Months Ended 9 Months Ended 12 Months Ended
Dec. 01, 2020
USD ($)
shares
Sep. 30, 2021
USD ($)
$ / shares
shares
Sep. 30, 2020
USD ($)
shares
Sep. 30, 2021
USD ($)
$ / shares
shares
Sep. 30, 2020
USD ($)
shares
Dec. 31, 2020
USD ($)
shares
Mar. 31, 2021
shares
Dec. 16, 2020
shares
Common Stock, Shares Authorized (in shares) | shares 75,000,000 75,000,000   75,000,000   75,000,000 [1]    
Reverse Stock Split, Rounding Adjustment (in shares) | shares 5,931              
Payments for Fractional Shares of Reverse Stock Split $ 0              
Number of Financial Institutions   1   1        
Accounts Receivable, Allowance for Credit Loss, Ending Balance   $ 49,000   $ 49,000   $ 124,000    
Accounts Receivable, Allowance for Credit Loss, Writeoff   115,000 $ 0 179,000 $ 173,000      
Revenue from Contract with Customer, Excluding Assessed Tax, Total   1,616,000 1,524,000 4,720,000 3,532,000      
Deferred Income   436,000   436,000   345,000    
Contract with Customer, Asset, after Allowance for Credit Loss, Total   0   0   0    
Capitalized Contract Cost, Net, Total   53,000   53,000   $ 32,000    
Capitalized Contract Cost, Amortization   13,000 58,000 47,000 538,000      
Capitalized Contract Cost, Impairment Loss       0        
Equity Method Investment, Other than Temporary Impairment   $ 0 $ 0 $ 0 $ 0      
Series A Preferred Stock [Member]                
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   1   1        
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   0   0       0
Series B Preferred Stock [Member]                
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   2,567,255 2,270,261 2,567,255 2,270,261 2,341,111    
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   39,279 34,735 39,279 34,735 35,819 [1]    
Conversion of Stock Exchange Ratio       65.36        
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ / shares   $ 1,000   $ 1,000        
Conversion of Stock, Conversion Rate (in dollars per share) | $ / shares   $ 15.30   $ 15.30        
Series C Preferred Stock [Member]                
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   1   1        
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   0   0   0 0  
Conversion of Stock Exchange Ratio       1        
Minimum [Member]                
Warranty Period (Year)       1 year        
Maximum [Member]                
Warranty Period (Year)       3 years        
Rental [Member]                
Revenue from Contract with Customer, Excluding Assessed Tax, Total   $ 261,000 $ 471,000 $ 950,000 $ 829,000      
Rental Program Equipment [Member]                
Revenue from Contract with Customer, Excluding Assessed Tax, Total   14,000   310,000        
Marketing Programs [Member]                
Contract with Customer, Liability, Total   $ 25,000   $ 25,000   $ 17,000    
Customer Concentration Risk [Member] | Revenue Benchmark [Member]                
Concentration Risk, Number of Customers       1 1      
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | One Customer [Member]                
Concentration Risk, Percentage   36.00% 40.00% 29.00% 45.00%      
Customer Concentration Risk [Member] | Accounts Receivable [Member]                
Concentration Risk, Number of Customers           1    
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Two Customers [Member]                
Concentration Risk, Percentage           37.00%    
Reverse Stock Split [Member]                
Stockholders' Equity Note, Stock Split, Conversion Ratio 10              
[1] The condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements as of that date.