Commitments and Contingencies - Operating leases and purchase obligations (Details) - USD ($)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Operating Leases
Rent expense under operating leases	$ 140,000	$ 113,000	$ 94,000
Operating leases future minimum payments due	135,000
Purchase Obligations
Purchase obligations on open purchase orders	1,100,000	$ 700,000	$ 900,000
Product Liability
Product liability insurance	$ 50,000,000