Intangible assets, net - Summary of Intangible Assets (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 18,212,000	$ 17,921,000
Accumulated amortization	(9,019,000)	(7,727,000)
Total	9,193,000	10,194,000
Patent costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,582,000	5,291,000
Developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	9,800,000	9,800,000
In-process research & development
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	1,580,000	1,580,000
Customer base
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	700,000	700,000
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 550,000	$ 550,000