Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 7,675	$ 6,329
Short-term investments, available-for-sale	32,297	64,195
Accounts receivable, net	660	2,256
Inventory	9,083	8,284
Prepaid expenses	3,149	3,584
Employee retention tax credit receivable	554	554
Other current assets	1,492	1,671
Total Current Assets	54,910	86,873
Restricted cash	1,354	1,141
Long-term investments, available-for-sale	0	3,865
Inventory, net of current portion	4,939	5,469
Property and equipment, net	8,815	9,542
Intellectual property, net	1,411	1,576
Net deferred tax assets	155	174
Operating lease right-of-use assets, net	4,888	4,950
Other long-term assets	1,899	2,463
Total Assets	78,371	116,053
Current Liabilities:
Accounts payable	4,281	3,348
Accrued employee compensation and benefits	3,887	4,508
Accrued expenses and other current liabilities	1,284	1,293
Operating lease liabilities - current portion	819	800
Deferred revenue	376	465
Total Current Liabilities	10,647	10,414
Long-Term Liabilities:
Contingent consideration	1,564	1,256
Noncurrent operating lease liabilities	4,657	4,738
Total Liabilities	16,868	16,408
Commitments and Contingencies (Note 14)
Stockholders' Equity:
Common stock $0.001 par value, 750,000,000 shares authorized at June 30, 2023 and December 31, 2022; 239,970,041 and 236,895,440 issued and outstanding at June 30, 2023 and December 31, 2022, respectively	240	237
Preferred stock, $0.01 par value, 25,000,000 shares authorized, no shares issued and outstanding at June 30, 2023 and December 31, 2022	0	0
Additional paid-in capital	966,335	962,731
Accumulated deficit	(903,815)	(860,935)
Accumulated other comprehensive loss	(1,257)	(2,388)
Total Stockholders' Equity	61,503	99,645
Total Liabilities and Stockholders' Equity	78,371	116,053
Intellectual Property [Member]
Current Assets:
Intellectual property, net	$ 1,411	$ 1,576