Note 12 - Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2016
Inventories	$ 116,673	$ 291,338	$ 302,600
Bad debts	13,799	21,171	3,400
Accrued liabilities	140,280	88,817	77,700
Prepaid expense	(59,085)	(73,120)	(8,900)
Depreciation and amortization	166,798	220,967	93,000
Research and development and other credit carryforwards	2,150,820	2,179,462	2,019,700
Net operating loss carryforward	59,852	520,087	1,303,000
Directors stock option plan	27,074	41,537	40,100
Total deferred tax asset	2,616,211	3,290,259	3,830,600
Valuation allowance	(47,319)	(500,000)	(500,000)
Reserve for uncertain tax positions	(395,000)
Total reserves & allowances	(442,319)	(500,000)	(500,000)
Net deferred tax asset	$ 2,173,892	$ 2,790,259	$ 3,330,600