INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carry-forward	$ 18,498	$ 14,996	$ 11,527
Inventory	115	52	21
Stock-based compensation	1,099	1,049	813
Start-up expenditures	199	221	243
Research and development credit carryforward	1,171	1,209	326
Accrued bonus	423	200	101
Severance liability	122	134
Investment in Panacea	360	40
Operating lease obligations	52	127
Other	29	22	20
Total deferred tax assets	22,068	18,050	13,051
Deferred tax liabilities:
Machinery and equipment	(237)	(239)	(215)
Patents and trademarks	(358)	(351)	(562)
Gain on investment	(13)	(104)	(612)
Accrued expense	(24)	(51)	(71)
Operating lease right-of-use assets	(52)	(126)
Other intangible assets	(224)	(189)	(153)
Total deferred tax liabilities	(908)	(1,060)	(1,613)
Valuation allowance	(21,198)	$ (16,990)	$ (11,438)
Net deferred taxes	$ (38)