CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 5,889	$ 6,053
Short-term investments		300
Accounts receivable, net	701	1,175
Inventories	599	968
Prepaid expenses and other	668	472
Total current assets	7,857	8,968
Property and equipment, net	121	197
Right-of-use lease asset	303	156
Other	17	78
Total assets	8,298	9,399
Current liabilities
Accounts payable	76	218
Deferred revenue	15	166
Short-term lease liability	201	166
PPP note payable, current	244
Accrued expenses and other	1,300	1,155
Total current liabilities	1,836	1,705
Long-term lease liability	103
PPP note payable	335
Convertible notes payable	3,092	2,858
Total liabilities	5,366	4,563
Commitments and contingencies (Note 9)
Stockholders’ equity
Preferred stock, $0.01 par value; 20,000 shares authorized; none issued and outstanding
Common stock, $0.001 par value; 120,000 shares authorized; 3,554 shares and 2,179 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively	3	2
Additional paid-in capital	245,548	243,281
Accumulated deficit	(242,619)	(238,447)
Total stockholders’ equity	2,932	4,836
Total liabilities and stockholders’ equity	$ 8,298	$ 9,399