Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.1
Note 2 - Summary of Significant Accounting Policies (Details Textual)
3 Months Ended 12 Months Ended
Dec. 01, 2020
USD ($)
shares
Mar. 31, 2021
USD ($)
$ / shares
shares
Mar. 31, 2020
USD ($)
shares
Dec. 31, 2020
USD ($)
shares
Dec. 16, 2020
shares
Common Stock, Shares Authorized (in shares) | shares   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      
Accounts Receivable, Allowance for Credit Loss, Ending Balance   $ 126,000   $ 124,000  
Accounts Receivable, Allowance for Credit Loss, Writeoff   64,000 $ 0    
Revenue from Contract with Customer, Excluding Assessed Tax, Total   1,450,000 1,304,000    
Deferred Income   274,000   345,000  
Contract with Customer, Asset, after Allowance for Credit Loss, Total   0   0  
Capitalized Contract Cost, Net, Total   33,000   $ 32,000  
Capitalized Contract Cost, Amortization   14,000 198,000    
Capitalized Contract Cost, Impairment Loss   0      
Equity Method Investment, Other than Temporary Impairment   $ 0 $ 0    
Series A Preferred Stock [Member]          
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   1      
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   0     0
Series B Preferred Stock [Member]          
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   2,414,183 2,135,098 2,341,111  
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   36,937 32,677 35,819 [1]  
Conversion of Stock Exchange Ratio   65.36      
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ / shares   $ 1,000      
Conversion of Stock, Conversion Rate (in dollars per share) | $ / shares   $ 15.30      
Series C Preferred Stock [Member]          
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares   1      
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares   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   $ 366,000 $ 421,000    
Rental Program Equipment [Member]          
Revenue from Contract with Customer, Excluding Assessed Tax, Total   230,000      
Marketing Programs [Member]          
Contract with Customer, Liability, Total   $ 16,000   $ 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   17.00% 48.00%    
Customer Concentration Risk [Member] | Accounts Receivable [Member]          
Concentration Risk, Number of Customers   1   1  
Customer Concentration Risk [Member] | Accounts Receivable [Member] | One Customer [Member]          
Concentration Risk, Percentage   18.00%      
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.