Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	$ (3,445)	$ (3,836)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation of property and equipment	180	167
Amortization and abandonment of patent and trademark rights	71	165
Equity-based compensation	58	88
Change in assets and liabilities:
Inventories	(480)	0
Prepaid expenses and other current assets	(33)	25
Accounts payable	236	(16)
Accrued expenses	(844)	512
Net cash used in operating activities	(4,257)	(2,895)
Cash flows from investing activities:
Purchase of property, equipment and construction in progress	(47)	(65)
Additions to patent and trademark rights	(145)	(75)
Sales and maturities of short-term and long-term marketable securities	0	(37)
Net cash used in investing activities	(192)	(177)
Cash flows from financing activities:
Payments on capital leases	(7)	(11)
Proceeds from sale of stock, net of issuance costs	5,242	6,385
Net cash provided by financing activities	5,235	6,374
Net increase in cash and cash equivalents	786	3,302
Cash and cash equivalents at beginning of period	2,156	803
Cash and cash equivalents at end of period	2,942	4,105
Supplemental disclosures of non-cash investing and financing cash flow information:
Issuance of common stock for accounts payable	0	38
Unrealized gain on marketable securities	111	21
Supplemental disclosure of cash flow information:
Cash paid for interest expense	$ 2	$ 3