REVENUE - Revenue by customer type and geographic area (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Product sales:
Total revenue	$ 10,546,612	$ 6,095,007	$ 29,048,825	$ 17,519,162
Product
Product sales:
Total revenue	10,245,642	5,728,463	27,921,940	16,155,459
Grant
Product sales:
Total revenue	300,970	366,544	1,126,885	1,363,703
United States | Product
Product sales:
Total revenue	261,500	80,000	997,000	146,800
United States | Grant
Product sales:
Total revenue	300,970	366,544	1,126,885	1,363,703
Germany | Product
Product sales:
Total revenue	4,818,029	3,445,632	14,271,239	10,242,943
All Other Countries | Product
Product sales:
Total revenue	5,166,113	2,202,831	12,653,701	5,765,716
Direct
Product sales:
Total revenue	6,334,158	4,271,520	18,996,560	12,792,882
Direct | Product
Product sales:
Total revenue	6,334,158	4,271,520	18,996,560	12,792,882
Direct | United States | Product
Product sales:
Total revenue	222,300	80,000	957,800	146,800
Direct | United States | Grant
Product sales:
Total revenue	0	0	0	0
Direct | Germany | Product
Product sales:
Total revenue	4,818,029	3,445,632	14,271,239	10,242,943
Direct | All Other Countries | Product
Product sales:
Total revenue	1,293,829	745,888	3,767,521	2,403,139
Distributors/Strategic Partners
Product sales:
Total revenue	3,911,484	1,456,943	8,925,380	3,362,577
Distributors/Strategic Partners | Product
Product sales:
Total revenue	3,911,484	1,456,943	8,925,380	3,362,577
Distributors/Strategic Partners | United States | Product
Product sales:
Total revenue	39,200	0	39,200	0
Distributors/Strategic Partners | United States | Grant
Product sales:
Total revenue	0	0	0	0
Distributors/Strategic Partners | Germany | Product
Product sales:
Total revenue	0	0	0	0
Distributors/Strategic Partners | All Other Countries | Product
Product sales:
Total revenue	3,872,284	1,456,943	8,886,180	3,362,577
United States Government Agencies
Product sales:
Total revenue	300,970	366,544	1,126,885	1,363,703
United States Government Agencies | Product
Product sales:
Total revenue	0	0	0	0
United States Government Agencies | United States | Product
Product sales:
Total revenue	0	0	0	0
United States Government Agencies | United States | Grant
Product sales:
Total revenue	300,970	366,544	1,126,885	1,363,703
United States Government Agencies | Germany | Product
Product sales:
Total revenue	0	0	0	0
United States Government Agencies | All Other Countries | Product
Product sales:
Total revenue	$ 0	$ 0	$ 0	$ 0