Note 1 - Basis of Presentation and Significant Accounting Policies (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Asset Retirement Obligation, Ending Balance	$ 138	$ 138		$ 134
Litigation Settlement, Amount Awarded to Other Party		$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)		$ 1.55
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	510	$ 510
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Total Forfeiture Adjusted Amount	$ 394	$ 394
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)		1 year 328 days
Share-based Payment Arrangement, Expense		$ 119	52
Proceeds from Stock Options Exercised		142	0
Share-based Payment Arrangement, Expense, Tax Benefit		$ 0	$ 0
Preferred Stock, Shares Issued, Total (in shares)	0	0		0
Cash and Cash Equivalents, at Carrying Value, Ending Balance	$ 5,845	$ 5,845		$ 7,619
Japan and the Netherlands [Member]
Cash and Cash Equivalents, at Carrying Value, Ending Balance	$ 3,100	$ 3,100
Series A Preferred Stock [Member]
Preferred Stock, Shares Issued, Total (in shares)	0	0	0	0
Preferred Stock, Shares Outstanding, Ending Balance (in shares)	0	0	0	0
Employee Stock Purchase Plan [Member]
Share-based Payment Arrangement, Expense		$ 1	$ 1
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	300,000	300,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)	100,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	106,710	106,710
Minimum [Member]
Lessor, Sales-type Lease, Term of Contract (Year)	3 years	3 years
Maximum [Member]
Lessor, Sales-type Lease, Term of Contract (Year)	5 years	5 years
One-time Termination Benefits [Member]
Restructuring Charges, Total		$ 101	$ 0

The forfeiture adjusted amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Aggregate number of common shares reserved for future issuance.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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