Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 19,543	$ 35,229
Restricted cash	5	5
Investments in debt securities- short term	4,415
Trade accounts receivable, net of allowance for doubtful accounts	303	120
Inventory	12	31
Prepaid expenses and other current assets	322	363
Total current assets	24,600	35,748
Investments in debt securities- long term	7,074
Property and equipment, net	8,819	11,767
Patents and trademarks, net	239	322
Equipment held for sale	585
Other assets	14	14
Total assets	41,331	47,851
Current liabilities:
Accounts payable	132	253
Accrued liabilities	775	270
Deferred revenue		31
Total current liabilities	907	554
Long-term liabilities
Other long-term liabilities	856	856
Total liabilities	1,763	1,410
Shareholders' equity:
Preferred Stock, $0.001 par value; 10,000,000 shares authorized; 0 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively
Common stock, $0.001 par value; 1,100,000,000 shares authorized; 914,449,957 and 914,206,832 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively	914	914
Warrants	18,179	18,179
Additional paid-in capital	286,832	286,276
Accumulated deficit	(266,284)	(258,854)
Accumulated other comprehensive income	2
Non-controlling interest in subsidiary	(75)	(74)
Total shareholders' equity	39,568	46,441
Total liabilities and shareholders' equity	$ 41,331	$ 47,851