Stock Plans and Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Allocated Stock Based Compensation Expense

Stock-based compensation expense was allocated based on the employees’ and non-employees’ functions as follows:

	Three Months Ended March 31,
	2020		2019
Cost of goods sold	$	71	$	111
Research and development		201		265
Sales and marketing		440		513
General and administrative		735		1,014
Total	$	1,447	$	1,903

Schedule of Weighted Average Assumptions Used in Black-Scholes Options Pricing Model

The weighted average assumptions used in the Black-Scholes options pricing model are as follows:

	Three Months Ended March 31,
	2020			2019
Expected dividend yield		0.0	%		0.0	%
Risk free interest rate		1.8	%		2.5	%
Expected stock price volatility		87.6	%		75.5	%
Expected term (years)		6.1			6.1

Summary of Restricted Stock Activity

A summary of restricted stock activity for the three months ended March 31, 2020 is as follows:

				Weighted
				Average
				Grant Date
	Shares			Fair Value
Unvested at December 31, 2019		229,913		$	3.76
Granted/purchased		36,367			10.40
Vested		(40,931	)		3.30
Canceled		-			-
Unvested at March 31, 2020		225,349		$	4.65

Employee Stock Purchase Plan

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Schedule of Weighted Average Assumptions Used in Black-Scholes Options Pricing Model

The fair value of the purchase right for the ESPP option is estimated on the date of grant using the Black-Scholes model with the following assumptions for the initial offering period:

Expected dividend yield	0.0	%
Risk free interest rate	1.6	%
Expected stock price volatility	107.9	%
Expected term (years)	0.4