Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Accounts receivable, allowance for doubtful accounts	$ 227,000	$ 274,000
Inventories, reserves	$ 840,000	$ 1,069,000
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 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)	11,482,064	10,872,428
Common stock, shares outstanding (in shares)	11,482,064	10,872,428