Note 12 - Fair Value - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Clene Nanomedicine contingent earn-out liability	$ 22		$ 75
Initial Stockholders contingent earn-out liability	3		10
Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	6,178		6,179
US Treasury Securities [Member]
Cash Equivalents	12,191		19,884
Money Market Funds [Member]
Cash Equivalents	5,660		5,113
Fair Value, Inputs, Level 1 [Member]
Clene Nanomedicine contingent earn-out liability	0		0
Initial Stockholders contingent earn-out liability	0		0
Fair Value, Inputs, Level 1 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	0		0
Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Cash Equivalents	5,660		5,113
Fair Value, Inputs, Level 2 [Member]
Clene Nanomedicine contingent earn-out liability	0		0
Initial Stockholders contingent earn-out liability	0		0
Fair Value, Inputs, Level 2 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	6,178		6,179
Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Cash Equivalents	12,191		19,884
Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 3 [Member]
Clene Nanomedicine contingent earn-out liability	22		75
Initial Stockholders contingent earn-out liability	3		10
Fair Value, Inputs, Level 3 [Member] | Us Treasury Securities with Maturity Greater than 90 Days but Less than 1 Year [Member]
Fair value	0		0
Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Cash Equivalents	0		0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Cash Equivalents	0		0
Common Stock Warrant Liability [Member]
Common stock warrant liabilities	2,790		1,481
Balance	1,481
Change in fair value	1,309
Balance	2,790
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 1 [Member]
Common stock warrant liabilities	0		0
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 2 [Member]
Common stock warrant liabilities	0		0
Common Stock Warrant Liability [Member] | Fair Value, Inputs, Level 3 [Member]
Common stock warrant liabilities	2,790		$ 1,481
Clene Nanomedicine Contingent Earn-out [Member]
Balance	75	$ 2,264
Change in fair value	(53)	55
Balance	22	2,319
Initial Stockholders Contingent Earn-out [Member]
Balance	10	291
Change in fair value	(7)	7
Balance	$ 3	$ 298