Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Accounts Receivable, Allowance for Credit Loss [Table Text Block]

	2019			2018
Balance, beginning of year	$	260		$	146
Provision		(56	)		120
Recoveries/write-offs		(185	)		(6	)
Balance, end of year	$	19		$	260

Schedule of Product Warranty Liability [Table Text Block]

	201 9			201 8
Balance, beginning of year	$	272		$	390
Warranty provision		71			333
Usage/Release		(128	)		(451	)
Balance, end of year	$	215		$	272

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Year Ended December 31,
	201 9			201 8
Net loss attributable to common stockholders	$	(23,030	)	$	(35,692	)
Weighted average common stock outstanding		7,239			1,068
Net loss per share attributable to common stockholders, basic and diluted	$	(3.18	)	$	(33.42	)

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

	Year Ended December 31,
	201 9		201 8
Common stock options		7,549		7,179
Convertible preferred stock		45,015		41,398
Unvested restricted stock units		471,252		92,245
Common stock warrant equivalents		3,197,208		2,077,871
		3,721,024		2,218,693