Note 10 - Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2021

Notes Tables

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
Cost of revenues	$	5,000	$	2,000	$	10,000	$	2,000
Selling, general and administrative		1,914,000		291,000		2,130,000		343,000
Research and development		180,000		21,000		217,000		36,000
	$	2,099,000	$	314,000	$	2,357,000	$	381,000

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life		Aggregate Intrinsic Value
Outstanding at December 31, 2020		889,636	$	8.57
Cancelled / Forfeited		503,050
Outstanding at June 30, 2021		386,461	$	11.88		7.4	$	--
Vested and expected to vest at June 30, 2021		335,786	$	9.15		7.3	$	--
Exercisable at June 30, 2021		244,211	$	10.31		7.1	$	--

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Number of Shares		Weighted-Average Exercise Price Per Share		Weighted- Average Remaining Contract Term
Balance at December 31, 2020		1,116,484	$	37.27		0.49
Warrants expired		463,236
Warrants exercised		--	$	--
Outstanding at June 30, 2021		653,248	$	6.97		1.90
Exercisable at June 30, 2021		653,248	$	6.97		1.90