Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current Assets:
Cash and cash equivalents	$ 24,828	$ 18,129
Short-term investments, available-for-sale	78,913	80,262
Accounts receivable, net	530	749
Inventories	9,141	8,634
Prepaid expenses	3,026	3,255
Employee retention tax credit receivable	1,311	1,311
Other current assets	935	957
Total Current Assets	118,684	113,297
Restricted cash	1,176	1,154
Long-term investments, available-for-sale	14,727	37,435
Inventories, net of current portion	7,487	7,074
Property and equipment, net	10,427	10,971
Intellectual property, net	7,009	9,892
Net deferred tax assets	273	288
Operating lease right-of-use assets, net	5,096	5,348
Other long-term assets	1,681	1,014
Total Assets	166,560	186,473
Current Liabilities:
Accounts payable	3,521	3,448
Accrued employee compensation and benefits	2,516	3,559
Accrued expenses and other current liabilities	1,479	1,617
Operating lease liabilities - current portion	604	683
Deferred revenue	533	543
Total Current Liabilities	8,653	9,850
Long-Term Liabilities:
Contingent consideration	2,217	2,371
Noncurrent operating lease liabilities	4,865	5,006
Total Liabilities	15,735	17,227
Commitments and Contingencies (Note 13)
Stockholders' Equity:
Common stock $0.001 par value, 750,000,000 shares authorized at March 31, 2022 and December 31, 2021; 236,415,239 and 235,218,552 shares issued and outstanding at March 31, 2022 and December 31, 2021, respectively	236	235
Preferred stock, $0.01 par value, 25,000,000 shares authorized, no shares issued and outstanding at March 31, 2022 and December 31, 2021	0	0
Additional paid-in capital	956,557	954,649
Accumulated deficit	(804,502)	(785,374)
Accumulated other comprehensive loss	(1,466)	(264)
Total Stockholders' Equity	150,825	169,246
Total Liabilities and Stockholders' Equity	166,560	186,473
Intellectual Property [Member]
Current Assets:
Intellectual property, net	$ 7,009	$ 9,892