Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.18	$ 0.18
Common stock, authorized (in shares)	175,000,000	175,000,000
Common stock, issued (in shares)	5,846,552	2,651,952
Common stock, outstanding (in shares)	5,846,552	2,651,952
Series A Convertible Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	4,000	4,000
Preferred stock, outstanding (in shares)	0	0
Preferred stock, issued (in shares)	0
Series B Convertible Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	25,000	0
Preferred stock, outstanding (in shares)	2,379	0
Preferred stock, issued (in shares)	2,379	0