Shareholders' Equity (Tables)

6 Months Ended

Jun. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Fair Values of Stock Option Grants Estimated with Weighted Average Assumptions

The fair values of our stock option grants were estimated with the following weighted average assumptions:

	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Dividend yield		0	%		0	%		0	%		0	%
Expected life	5.8 years			5.2 years			5.9 years			5.3 years
Expected volatility		64	%		55	%		64	%		54	%
Risk-free interest rate		2.2	%		2.7	%		2.2	%		2.5	%

Stock-Based Compensation Expense

The impact on our results of operations from stock-based compensation expense was as follows (in thousands, except per share amounts):  

	Three Months Ended June 30,					Six Months Ended June 30,
	2019		2018			2019			2018
Cost of revenue — professional engineering service	$	3	$	8		$	9		$	19
Selling, general and administrative		10		(80	)		198			184
Research and development		2		56			(24	)		112
Total stock-based compensation expense	$	15	$	(16	)	$	183		$	315
Per diluted share	$	-	$	-		$	0.01		$	0.02

Summary of Stock Option Activity

The following table summarizes stock option activity under the Plans:

						Weighted Average
						Remaining
				Weighted Average		Contractual Life		Aggregate
	Number of Shares			Exercise Price		(in years)		Intrinsic Value
Balance at December 31, 2018		1,390,012		$	4.77		6.83	$	—
Granted		676,500			1.88
Exercised		—			—
Forfeited		(181,995	)		4.85
Expired		(145,433	)		4.34
Balance at June 30, 2019		1,739,084		$	3.67		6.49	$	—
Vested and expected to vest at June 30, 2019		1,502,904		$	3.91		6.00	$	—
Exercisable at June 30, 2019		893,634		$	4.92		3.72	$	—

Summary of Certain Additional Information about Stock Options

The following table summarizes certain information about stock options:

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
Weighted average grant-date fair value of options granted during the period	$	1.35	$	1.77	$	1.88	$	2.80
Options in-the-money (in shares)		—		19,550		—		1,755,762
Aggregate intrinsic value of options exercised during the period	$	—	$	1,578	$	—	$	57,833

Summary of Restricted Stock Unit Activity

The following table summarizes RSU activity under the Plans:

	Number of			Weighted Average
	Shares			Award Price
Unvested at December 31, 2018		186,516		$	2.88
Granted		225,693			1.44
Vested		(101,679	)		2.63
Forfeited		(31,831	)		4.58
Unvested at June 30, 2019		278,699		$	1.61
Expected to vest after June 30, 2019		255,877		$	1.62

Summary of Shares of Common Stock Reserved for Future Issuance under Plans

The following table summarizes our shares of common stock reserved for future issuance under the Plans as of June 30, 2019:

	June 30, 2019
Stock options outstanding		1,739,084
Restricted stock units outstanding		278,699
Stock options and restricted stock units available for future grant		1,532,966
Common stock reserved for future issuance		3,550,749