Note 12 - Income Taxes - Significant Portion of Net Deferred Tax Asset (Details) - USD ($)	Sep. 30, 2019	Sep. 30, 2018
Net operating loss carryforwards	$ 12,682,000	$ 13,644,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	5,856,000	5,805,000
Share-based compensation	506,000	532,000
Equipment	(78,000)	(41,000)
Patents	24,000	35,000
Accruals and other	1,222,000	818,000
State tax deduction	(6,000)	(5,000)
Federal AMT Credit	24,000	53,000
Allowances	169,000	133,000
Gross deferred tax asset	20,399,000	20,974,000
Less valuation allowance	(15,012,000)	(15,017,000)
Total deferred tax assets, net of valuation allowance	$ 5,387,000	$ 5,957,000