Note 12 - Segment Reporting - Sales to Customers (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net revenues	$ 13,047,000	$ 9,672,000
UNITED STATES
Net revenues	6,787,000	4,854,000
Asia - Other [Member]
Net revenues	2,108,000	1,717,000
Europe [Member]
Net revenues	1,233,000	1,165,000
CHINA
Net revenues	2,346,000	1,143,000
All Other Countries [Member]
Net revenues	$ 573,000	$ 793,000