Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net loss	$ (1,456)	$ (1,271)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	12	28
Stock-based compensation	181	180
Amortization of premium on short-term investments	15	30
Other		15
Changes in operating assets and liabilities:
Accounts receivable	(13)	13
Inventories	27	(61)
Prepaid expenses and other current assets	(180)	(144)
Accounts payable	(136)	(26)
Accrued liabilities	(183)	3
Net cash used in operating activities	(1,733)	(1,233)
Cash flows from investing activities:
Proceeds from sales and maturities of short-term investments	641	1,777
Purchases of short-term investments	(4,169)	(3,970)
Purchase of property and equipment	(2)	(5)
Net cash used in investing activities	(3,530)	(2,198)
Cash flows from financing activities:
Proceeds from sale of common stock in a public offering, net of related costs of $33	276
Net cash provided by financing activities	276
Net decrease in cash and cash equivalents	(4,987)	(3,431)
Cash and cash equivalents at beginning of period	9,403	6,211
Cash and cash equivalents at end of period	$ 4,416	$ 2,780