Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 12,689	$ 21,352
Accounts receivable, net of allowance for doubtful accounts of $6 and $2 at December 31, 2017 and 2016, respectively	95	74
Inventory	191	135
Prepaid expenses	340	356
Total current assets	13,315	21,917
Property and equipment, net	169	111
Other assets	54	54
Total assets	13,538	22,082
Current liabilities:
Accounts payable	902	525
Accrued expenses and other current liabilities	1,263	848
Deferred revenue	167	71
Total current liabilities	2,332	1,444
Deferred rent	81	56
Total liabilities	2,413	1,500
Stockholders’ equity:
Preferred stock, $0.001 par value, 25,000,000 and 50,000,000 shares authorized as of December 31, 2017 and 2016, respectively; no shares issued and outstanding as of December 31, 2017 and 2016	0	0
Common stock, $0.001 par value, 100,000,000 and 750,000,000 shares authorized as of December 31, 2017 and 2016 respectively; 38,218,660 and 38,131,303 shares issued and outstanding as of December 31, 2017 and 2016, respectively	38	38
Additional paid-in capital	83,537	80,686
Accumulated deficit	(72,450)	(60,142)
Total stockholders’ equity	11,125	20,582
Total liabilities and stockholders’ equity	$ 13,538	$ 22,082