REVENUE - Revenue by customer type and geographic area (Details) - USD ($)	3 Months Ended												12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Product sales:
Total revenue	$ 10,782,195	$ 9,760,416	$ 12,024,069	$ 10,598,847	$ 11,955,776	$ 10,546,612	$ 9,794,903	$ 8,707,310	$ 7,430,311	$ 6,095,007	$ 6,232,526	$ 5,191,629	$ 43,165,527	$ 41,004,601	$ 24,949,473
Product
Product sales:
Total revenue													40,108,567	39,452,502	22,765,854
Grant
Product sales:
Total revenue													3,056,960	1,552,099	2,183,619
United States | Product
Product sales:
Total revenue													1,689,867	1,341,200	220,100
United States | Grant
Product sales:
Total revenue													3,056,960	1,552,099	2,183,619
Germany | Product
Product sales:
Total revenue													21,006,432	20,257,410	14,396,418
All other countries | Product
Product sales:
Total revenue													17,412,268	17,853,892	8,149,336
Direct
Product sales:
Total revenue													27,041,855	26,681,329	17,764,047
Direct | Product
Product sales:
Total revenue													27,041,855	26,681,329	17,764,047
Direct | United States | Product
Product sales:
Total revenue													189,167	1,148,300	220,100
Direct | United States | Grant
Product sales:
Total revenue													0	0	0
Direct | Germany | Product
Product sales:
Total revenue													21,006,432	20,257,410	14,396,418
Direct | All other countries | Product
Product sales:
Total revenue													5,846,256	5,275,619	3,147,529
Distributors/Strategic Partners
Product sales:
Total revenue													13,066,712	12,771,173	5,001,807
Distributors/Strategic Partners | Product
Product sales:
Total revenue													13,066,712	12,771,173	5,001,807
Distributors/Strategic Partners | United States | Product
Product sales:
Total revenue													1,500,700	192,900	0
Distributors/Strategic Partners | United States | Grant
Product sales:
Total revenue													0	0	0
Distributors/Strategic Partners | Germany | Product
Product sales:
Total revenue													0	0	0
Distributors/Strategic Partners | All other countries | Product
Product sales:
Total revenue													11,566,012	12,578,273	5,001,807
United States Government Agencies
Product sales:
Total revenue													3,056,960	1,552,099	2,183,619
United States Government Agencies | Product
Product sales:
Total revenue													0	0	0
United States Government Agencies | United States | Product
Product sales:
Total revenue													0	0	0
United States Government Agencies | United States | Grant
Product sales:
Total revenue													3,056,960	1,552,099	2,183,619
United States Government Agencies | Germany | Product
Product sales:
Total revenue													0	0	0
United States Government Agencies | All other countries | Product
Product sales:
Total revenue													$ 0	$ 0	$ 0