Income Taxes - Deferred tax assets and liabilities component (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Deferred tax assets:
Reserves and accruals	$ 698,233	$ 690,148	$ 730,015
Research and development credit	1,589,247	1,331,170	1,318,977
NOL carryforwards - fed/state	2,192,018	2,590,791	2,982,246
Depreciation	(807,522)	(826,724)	(863,796)
Stock options	5,296	348,624	345,608
Gross deferred tax assets	3,677,272	4,134,009	4,513,050
Less : Valuation allowance	(3,471,164)	(3,922,620)	(4,296,553)
Total deferred tax assets	206,108	211,389	216,497
Deferred tax liabilities:
Depreciation	(335,797)	(341,040)	(346,091)
Total deferred tax liabilities	(335,797)	(341,040)	(346,091)
Net deferred tax (liability) asset	$ (129,689)	$ (129,651)	$ (129,594)