Consolidated Statements Of Cash Flows (USD $)	6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Operating activities
Net loss	$ (4,554,000)	$ (4,501,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	623,000	605,000
Amortization of stock issued for services	24,000	0
Depreciation and amortization	216,000	234,000
Changes in operating assets and liabilities:
Accounts receivable	34,000	(31,000)
Inventories	(28,000)	(140,000)
Prepaid expenses	(12,000)	72,000
Accounts payable and accrued liabilities	935,000	269,000
Deferred revenue	0	312,000
Deferred rent	5,000	(4,000)
Net cash used in operating activities	(2,757,000)	(3,184,000)
Investing activities
Investment in patents	(79,000)	(142,000)
Purchases of property, plant and equipment	(9,000)	(10,000)
Net cash used in investing activities	(88,000)	(152,000)
Financing activities
Net proceeds from the sale of common stock	1,677,000	2,367,000
Net proceeds from exercise of stock options and warrants	0	454,000
Net cash provided by financing activities	1,677,000	2,821,000
Net decrease in cash and cash equivalents	(1,168,000)	(515,000)
Cash and cash equivalents at beginning of period	1,794,000	2,193,000
Cash and cash equivalents at end of period	626,000	1,678,000
Supplemental disclosure of cash flow information
Cash paid for taxes	1,000	2,400
Supplemental disclosure of non-cash investing and financing activities
Common stock issued for prepaid services	97,000	0
Common stock issued under stock purchase agreement	$ 296,000	$ 0