Note 2 - Summary of Significant Accounting Policies - Revenues (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net revenues	$ 3,200,000	$ 2,962,000
Device [Member] | AXP [Member]
Net revenues	2,232,000	1,322,000
Device [Member] | BioArchive [Member]
Net revenues	496,000	1,014,000
Device [Member] | CAR-TXpress [Member]
Net revenues	235,000	307,000
Device [Member] | Manual Disposables [Member]
Net revenues	203,000	300,000
Device [Member] | Other Subsegments [Member]
Net revenues	34,000	19,000
Device Revenue [Member]
Net revenues	2,741,000	2,478,000
Device Revenue [Member] | Device [Member] | AXP [Member]
Net revenues	2,208,000	1,267,000
Device Revenue [Member] | Device [Member] | BioArchive [Member]
Net revenues	164,000	599,000
Device Revenue [Member] | Device [Member] | CAR-TXpress [Member]
Net revenues	152,000	307,000
Device Revenue [Member] | Device [Member] | Manual Disposables [Member]
Net revenues	203,000	300,000
Device Revenue [Member] | Device [Member] | Other Subsegments [Member]
Net revenues	14,000	5,000
Service [Member]
Net revenues	368,000	470,000
Service [Member] | Device [Member] | AXP [Member]
Net revenues	24,000	55,000
Service [Member] | Device [Member] | BioArchive [Member]
Net revenues	332,000	415,000
Service [Member] | Device [Member] | CAR-TXpress [Member]
Net revenues	12,000
Service [Member] | Device [Member] | Manual Disposables [Member]
Net revenues
Service [Member] | Device [Member] | Other Subsegments [Member]
Net revenues
Other [Member]
Net revenues	91,000	14,000
Other [Member] | Device [Member] | AXP [Member]
Net revenues
Other [Member] | Device [Member] | BioArchive [Member]
Net revenues
Other [Member] | Device [Member] | CAR-TXpress [Member]
Net revenues	71,000
Other [Member] | Device [Member] | Manual Disposables [Member]
Net revenues
Other [Member] | Device [Member] | Other Subsegments [Member]
Net revenues	$ 20,000	$ 14,000