Note 7 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Share-based Compensation, Stock Options, Activity [Table Text Block]

	Year Ended					Year Ended
	December 31, 201 8					December 31, 201 7
				Wtd. Avg.					Wtd. Avg.
				Exercise					Exercise
	Shares			Price		Shares			Price
Outstanding at beginning of year		2,390,012		$	1.85		2,513,861		$	1.78
Granted		––			––		155,000			2.93
Exercised		(330,983	)		1.36		(131,427	)		1.17
Forfeited		(15,627	)		4.34		(52,932	)		3.45
Expired - vested		––			––		(94,490	)		1.78
Outstanding at end of year		2,043,402		$	1.91		2,390,012		$	1.85
Stock options exercisable at year end		1,661,999		$	1.87		1,583,585		$	1.72

	Year Ended					Year Ended
	December 31, 2018					December 31, 2017
				Wtd. Avg.				Wtd. Avg.
				Exercise				Exercise
	Shares			Price		Shares		Price
Outstanding at beginning of year		999,997		$	1.64		999,997	$	1.64
Granted		––			––		––		––
Exercised		(35,000	)		1.64		––		––
Outstanding at end of year		964,997		$	1.64		999,997	$	1.64
Stock options exercisable at year end		465,001		$	1.64		––	$	––

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

Range of Exercise Prices				Number Outstanding at December 31, 201 8		Weighted Average Remaining Contractual Life		Weighted Average Exercise Price
$	0.49	-	1.00		3,571		2.91	$	.49
$	1.01	-	1.50		412,073		1.91	$	1.24
$	1.51	-	2.50		1,549,367		6.52	$	1.94
$	2.51	-	8.60		78,391		6.69	$	4.99
					2,043,402		5.59	$	1.91

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Year Ended					Year Ended
	December 31, 201 8					December 31, 201 7
				Wtd. Avg.					Wtd. Avg.
				Grant Date					Grant Date
	Shares			Fair Value		Shares			Fair Value
Outstanding at beginning of year		237,926		$	1.79		98,439		$	1.90
Granted		181,268			7.02		207,350			1.76
Vested		(116,647	)		1.81		(51,563	)		1.90
Forfeited		(22,628	)		3.95		(16,300	)		1.76
Non-vested at end of year		279,919		$	5.00		237,926		$	1.79

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Year Ended December 31,
(In thousands)	2018		201 7
Research and development costs	$	260	$	237
Sales and marketing costs		269		231
General and administrative costs		809		638
Cost of product sales		181		164
Total	$	1,519	$	1,270