Note 13 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Research and development credit	$ 4,712	$ 5,479
Deferred Tax Assets, Valuation Allowance	9,378	$ 8,313
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Deferred Tax Assets, Net, Total	7,373
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	32,817
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	1,262
Research and development credit	2,500
State and Local Jurisdiction [Member]
Research and development credit	$ 119