Note 10 - Income Taxes - Significant Portion of Net Deferred Tax Asset (Details) - USD ($)	Sep. 30, 2017	Sep. 30, 2016
Net operating loss carryforwards	$ 16,443,000	$ 16,410,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	2,559,000	2,461,000
Share-based compensation	898,000	598,000
Equipment	(80,000)	(23,000)
Patents	69,000	102,000
Accruals and other	546,000	832,000
State tax deduction	(7,000)	(7,000)
Federal AMT Credit	52,000	52,000
Allowances	157,000	211,000
Gross deferred tax asset	20,637,000	20,636,000
Less valuation allowance	(12,306,000)	(12,109,000)
Total deferred tax assets, net of valuation allowance	$ 8,331,000	$ 8,527,000