Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, allowance for doubtful accounts	$ 227,000	$ 226,000
Inventories, reserves	356,000	350,000
Debt discount	$ 22,000	$ 46,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	5,768,885	2,843,601
Common stock, shares outstanding (in shares)	5,768,885	2,843,601
Convertible Promissory Note [Member]
Debt discount	$ 4,031,000	$ 5,195,000