Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Statement of Cash Flows [Abstract]
Net loss	$ (11,419)	$ (7,090)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation	250	486
Amortization of intangible assets	66	79
Gain on disposal of property and equipment	(28)	(2)
Non-cash share-based compensation expense	506	481
Realized loss on warrant exchange	4,967	0
Inventory write-downs	25	303
Non-cash deferred rent	(31)	0
Change in:
Accounts receivable, net	(30)	27
Inventory	(7)	150
Other current assets	(194)	899
Other assets		4
Accounts payable	19	(1,046)
Accrued liabilities	(230)	(771)
Deferred revenue		(581)
Billings in excess of costs and estimated earnings on uncompleted contracts	(560)	765
Net cash used in operating activities	(6,666)	(6,296)
Cash flows from investing activities
Decrease in restricted cash	0	1
Proceeds on sale of property and equipment	28	2
Purchases of property and equipment	(109)	(86)
Net cash used in investing activities	(81)	(83)
Cash flows from financing activities
Principal payments under capital leases and long-term debt	(15)	(75)
Net proceeds from issuance of common stock and warrants	13,851	5,607
Net cash provided by (used in) financing activities	13,836	5,532
Net increase (decrease) in cash and cash equivalents	7,089	(847)
Cash and cash equivalents, at beginning of period	5,375	6,850
Cash and cash equivalents, at end of period	12,464	6,003
Supplemental disclosure of cash flow information
Cash paid for interest	1	8
Supplemental schedule of non-cash investing and financing activities
Other non-cash additions to property and equipment	29	386
Issuance of common stock for exchange of warrants	9,869	0
Warrant liability	$ 0	$ 3,755