Condensed Consolidated Balance Sheets - USD ($)	Apr. 30, 2019	Jul. 31, 2018
Current assets
Cash and cash equivalents	$ 340,000	$ 851,000
Accounts receivable	134,000	275,000
Inventories, net	195,000	197,000
Restricted cash	75,000	75,000
Prepaid expenses	28,000	58,000
Total current assets	772,000	1,456,000
Property, plant and equipment, net	388,000	461,000
Patents, net	550,000	658,000
Total assets	1,710,000	2,575,000
Current liabilities
Accounts payable	386,000	608,000
Accrued liabilities	137,000	170,000
Promissory note payable		503,000
Total current liabilities	523,000	1,281,000
Deferred rent	7,000	13,000
Total liabilities	530,000	1,294,000
Stockholders' equity
Preferred stock, $0.01 par value: 5,000,000 shares authorized, no shares issued and outstanding
Common stock, $0.01 par value: 100,000,000 shares authorized, 74,113,371 shares issued and outstanding at April 30, 2019, and 68,248,158 shares issued and outstanding at July 31, 2018	741,000	683,000
Additional paid-in capital	123,098,000	117,522,000
Accumulated deficit	(122,659,000)	(116,924,000)
Total stockholders' equity	1,180,000	1,281,000
Total liabilities and stockholders' equity	$ 1,710,000	$ 2,575,000