Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 35,229	$ 41,309
Restricted cash	5	5
Trade accounts receivable, net of allowance for doubtful accounts	120	157
Inventory	31	391
Prepaid expenses and other current assets	363	326
Total current assets	35,748	42,188
Property and equipment, net	11,767	12,465
Patents and trademarks, net	322	408
Other assets	14	14
Total assets	47,851	55,075
Current liabilities:
Short-term debt
Accounts payable	253	92
Accrued liabilities	270	365
Deferred revenue	31	7
Total current liabilities	554	464
Long-term liabilities
Other long-term liabilities	856	856
Total liabilities	2,335	3,512
Shareholders' equity:
Preferred Stock, $0.001 par value; 10,000,000 shares authorized; 0 shares issued and outstanding at December 31, 2018 and December 31, 2017, respective
Common stock, $0.001 par value; 1,100,000,000 shares authorized; 914,206,832 and 908,768,116 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	914	909
Warrants	18,179	18,179
Additional paid-in capital	279,306	277,924
Accumulated deficit	(252,809)	(245,376)
Non-controlling interest in subsidiary	(74)	(73)
Total shareholders' equity	45,516	51,563
Total liabilities and shareholders' equity	47,851	55,075
Warrant [Member]
Current liabilities:
Included in current liabilities
Long-term liabilities
Warrant liabilities, long-term	925	2,192
Call Option [Member]
Current liabilities:
Included in current liabilities