Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 33,871	$ 35,229
Restricted cash	5	5
Trade accounts receivable	124	120
Inventory	63	31
Prepaid expenses and other current assets	311	363
Total current assets	34,374	35,748
Property and equipment, net	11,727	11,767
Patents and trademarks, net	301	322
Other assets	14	14
Total assets	46,416	47,851
Current liabilities:
Accounts payable	150	253
Accrued liabilities	516	270
Deferred revenue	28	31
Total current liabilities	694	554
Long-term liabilities:
Other long term liabilities	856	856
Total liabilities	1,550	1,410
Shareholders' equity:
Preferred Stock, $0.001 par value; 10,000,000 shares authorized; 0 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively
Common stock, $0.001 par value; 1,100,000,000 shares authorized; 914,316,624 and 914,206,832 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	914	914
Warrants	18,179	18,179
Additional paid-in capital	286,469	286,276
Accumulated deficit	(260,622)	(258,854)
Non-controlling interest in subsidiary	(74)	(74)
Total shareholders' equity	44,866	46,441
Total liabilities and shareholders' equity	$ 46,416	$ 47,851