Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 8,132,000	$ 11,703,000
Accounts receivable	946,000	924,000
Prepaid expenses and other current assets	845,000	758,000
Inventories	63,000	25,000
Total current assets	9,986,000	13,410,000
Property and equipment, net	318,000	353,000
Other assets	49,000	65,000
Total assets	10,353,000	13,828,000
Current liabilities:
Accounts payable	1,595,000	1,158,000
Accrued liabilities	2,164,000	2,588,000
Short-term debt	194,000	193,000
Other current liabilities	32,000	39,000
Total current liabilities	3,985,000	3,978,000
Total liabilities	5,051,000	5,090,000
Non-current liabilities:
Long-term debt	1,050,000	1,099,000
Other non-current liabilities	16,000	13,000
Commitments and contingencies (Note 3)
Stockholders' equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized, none issued and outstanding at March 31, 2020 and December 31, 2019
Common stock, par value $0.001 per share, 150,000,000 shares authorized at March 31, 2020 and December 31, 2019; 97,288,657 and 97,286,157 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	97,000	97,000
Additional paid-in capital	431,072,000	430,802,000
Accumulated deficit	(425,867,000)	(422,161,000)
Total stockholders' equity	5,302,000	8,738,000
Total liabilities and stockholders' equity	$ 10,353,000	$ 13,828,000