Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 5,358	$ 12,689
Accounts receivable, net of allowance for doubtful accounts of $9 and $6 at December 31, 2018 and 2017, respectively	274	95
Inventory	141	191
Prepaid expenses	445	340
Total current assets	6,218	13,315
Property and equipment, net	145	169
Other assets	54	54
Total assets	6,417	13,538
Current liabilities:
Accounts payable	1,020	902
Accrued expenses and other current liabilities	1,528	1,263
Deferred revenue		167
Total current liabilities	2,548	2,332
Deferred rent	77	81
Total liabilities	2,625	2,413
Stockholders’ equity:
Preferred stock, $0.001 par value, 25,000,000 shares authorized as of December 31, 2018 and 2017; no shares issued and outstanding as of December 31, 2018 and 2017
Common stock, $0.001 par value, 100,000,000 shares authorized as of December 31, 2018 and 2017; 43,611,240 and 38,218,660 shares issued and outstanding as of December 31, 2018 and 2017, respectively	43	38
Additional paid-in capital	90,110	83,537
Accumulated deficit	(86,361)	(72,450)
Total stockholders’ equity	3,792	11,125
Total liabilities and stockholders’ equity	$ 6,417	$ 13,538