Note 11 - Summary of Stock Options (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

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

	Three Months Ended March 31, 2020
						Weighted
				Weighted		Average
	Number			Average		Remaining		Aggregate
	of			Exercise		Contractual		Intrinsic
	Shares			Price		Term (years)		Value
Options outstanding, beginning of period		10,087,678		$	2.22		9.9	$	3,928,715
Options granted		468,000		$	0.88
Options exercised		-
Options canceled		(123,024	)	$	20.25
Options outstanding, end of period		10,432,654		$	1.95		9.7	$	-
Vested and exercisable and expected to vest, end of period		9,404,561		$	2.04		9.7	$	-
Vested and exercisable, end of period		833,785		$	9.63		9.6	$	-

Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

							Weighted
			Number		Weighted		Average		Number		Weighted
			Outstanding		Average		Remaining		Exercisable		Average
Range of			as of		Exercise		Contractual		as of		Exercise
Exercise Prices			March 31, 2020		Price		Term (Years)		March 31, 2020		Price
$0.69	-	$0.89		10,238,979	$	0.86		9.7		813,153	$	0.87
$1.09	-	$1.36		155,000	$	1.26		9.9		-	$	-
$38.00	-	$58.00		1,600	$	55.81		9.2		-	$	-
$100.00	-	$197.00		20,352	$	141.85		8.6		9,174	$	147.74
$202.00	-	$283.00		743	$	251.21		7.6		392	$	254.90
$311.00	-	$382.00		2,625	$	344.68		8.4		1,238	$	345.28
$430.00	-	$497.00		6,707	$	454.33		7.3		4,281	$	455.78
$501.00	-	$567.00		3,215	$	537.49		7.1		2,432	$	536.76
$600.00	-	$661.00		1,392	$	602.19		5.8		1,375	$	601.46
$700.00	-	$792.00		1,937	$	767.72		6.6		1,636	$	767.47
$992.00	-	$992.00		104	$	992.00		2.8		104	$	992.00
Total:				10,432,654	$	1.95		9.7		833,785	$	9.63

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended
	March 31,
	2020		2019
Expected term (in years)		5		5
Average volatility		73%		73%
Risk-free interest rate		0.45%		2.53%
Dividend yield		0%		0%

	Three Months Ended
	March 31,
	2020		2019
Expected term (in years)		5		5
Average volatility		73%		73%
Risk-free interest rate		1.39%		2.49%
Dividend yield		0%		0%

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

	Three Months Ended
	March 31,
	2020		2019
Cost of revenue	$	60	$	32
Research and development		87		40
Selling, general and administrative		564		424
Total		710	$	496

2017 Employee Stock Purchase Plan [Member]

Notes Tables

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Three Months Ended
	March 31,
	2020		2019
Expected term (in years)		0.25		0.25
Average volatility		124%		74%
Risk-free interest rate		1.54%		2.45%
Dividend yield		0%		0%