Note 4 - Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property and equipment, gross	$ 788	$ 789
Less accumulated depreciation	(674)	(619)
Property and equipment, net	114	170
Computer Equipment and Software [Member]
Property and equipment, gross	161	161
Laboratory and Manufacturing Equipment [Member]
Property and equipment, gross	574	575
Furniture and Fixtures [Member]
Property and equipment, gross	27	27
Leasehold Improvements [Member]
Property and equipment, gross	$ 26	$ 26

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-SubTopic 10
-Topic 360
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482099/360-10-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481372/852-10-55-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(8))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 360
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480842/942-360-50-1

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