Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Schedule of Product Warranty Liability [Table Text Block]

	Year Ended December 31,
	2022			2021
Beginning balance	$	80		$	—
Add: Accruals for warranties issued during the period		42			80
Less: Adjustment for inventory at cost and excessive and obsolete inventory		(72	)		—
Ending balance	$	50		$	80

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Year Ended December 31,
	2022		2021		2020
Common stock warrants		7,303,832		—		612,310
Common stock options		5,250,696		5,996,813		5,039,194
Restricted stock units		—		—		111,305
Total		12,554,528		5,996,813		5,762,809