Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used to Compute Share-Based Compensation Costs for Stock Options Granted

The assumptions used to compute the share-based compensation costs for the stock options granted during the years ended December 31, 2021 and 2020, using the Black-Scholes option pricing model, were as follows:

	Year Ended December 31,
	2021			2020
Weighted average grant date fair value of    stock options	$	5.94		$	2.93
Assumptions
Risk-free interest rate (weighted average)		0.87	%		0.44	%
Expected dividend yield		—			—
Weighted average expected life (years)		6.2			6.2
Volatility (weighted average)		74.5	%		80.8	%
Forfeiture rate		12.0	%		12.0	%

Assumptions Used Estimate Fair Value of Employee Stock Purchase Plans

Following is a schedule of the shares purchased, the fair value per share, and the Black-Scholes model assumptions for each offering period:

	September 30,			March 31,			September 30,			March 31,
Offering Period Ended	2021			2021			2020			2020
Shares purchased for offering    period		5,360			4,668			4,184			1,536
Fair value per share	$	1.90		$	1.25		$	1.75		$	2.28
Assumptions
Risk-free interest rate (average)		0.05	%		0.12	%		0.29	%		1.84	%
Expected dividend yield		—			—			—			—
Weighted average expected life    (years)		0.5			0.5			0.5			0.5
Volatility (average)		44.6	%		47.1	%		86.8	%		86.3	%

Non-Cash Stock-Based Compensation Expenses

Non-cash stock-based compensation expenses related to stock options, restricted stock grants and the ESPP were recorded in the financial statements as follows (in thousands):

	Year Ended December 31,
	2021		2020
Cost of sales	$	1	$	—
Sales and marketing		901		549
Research and development		965		559
General and administrative		2,981		1,956
Total non-cash stock compensation expense	$	4,848	$	3,064

Summary of Outstanding Stock Options and Related Activity

A summary of the Company’s stock options outstanding under the 2015 OEIP and 2005 Plan as of December 31, 2021 and 2020 and the activity during the years ended herein are as follows (in thousands except per share amounts):

	Shares			Weighted Avg. Exercise Price		Wtd. Avg. Remaining Contractual Life (Yrs)		Aggregate Intrinsic Value
Outstanding as of December 31, 2020		205		$	3.95
Granted		20		$	5.94			$	-
Exercised		(21	)	$	3.12			$	55
Forfeited		(8	)	$	2.99			$	20
Expired		(2	)	$	16.28			$	-
Outstanding as of December 31, 2021		194		$	3.95		4.9	$	218
Vested and expected to vest at December 31, 2021		181		$	4.03		4.9	$	211
Exercisable as of December 31, 2021		140		$	4.04		3.6	$	163

Summary of Outstanding Restricted Stock Awards and Related Activity

A summary of the Company’s restricted stock awards outstanding under the 2015 OEIP and 2005 Plan as of December 31, 2021 and 2020, and the activity during years ended therein, are as follows (in thousands, except weighted average grant date fair value):

				Weighted average
	Number			grant date
	of shares			fair value
Unvested at December 31, 2019		1,559		$	1.98
Granted		1,000		$	6.40
Vested		(857	)	$	2.99
Canceled and forfeited		—		$	-
Unvested at December 31, 2020		1,702		$	4.07
Granted		1,287		$	7.02
Vested		(1,027	)	$	4.47
Canceled and forfeited		(295	)	$	5.60
Unvested at December 31, 2021		1,667		$	5.83