Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and equipment, Gross		$ 7,796,135	$ 7,044,821
Less accumulated depreciation		(6,574,308)	(6,209,284)
Property and equipment, net	$ 201,762	1,221,827	835,537
Leasehold Improvements
Property and equipment, Gross		745,800	729,504
Laboratory and Manufacturing [Member]
Property and equipment, Gross		4,829,323	4,109,367
Computer Equipment [Member]
Property and equipment, Gross		1,520,713	1,505,651
Officer Equipment [Member]
Property and equipment, Gross		$ 700,299	$ 700,299

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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