Note 13 - Revenues - Remaining Performance Obligations 2 (Details)	Dec. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Amount	$ 4,702,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 1,958,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 1,493,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 529,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 385,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 337,000
Service [Member]
Revenue, Remaining Performance Obligation, Amount	$ 1,664,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 927,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 462,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 189,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 86,000
Service [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Device Revenue [Member]
Revenue, Remaining Performance Obligation, Amount	$ 1,505,000	[1]
Device Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year	[1]
Revenue, Remaining Performance Obligation, Amount	$ 732,000	[1]
Device Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year	[1]
Revenue, Remaining Performance Obligation, Amount	$ 732,000	[1]
Device Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year	[1]
Revenue, Remaining Performance Obligation, Amount	$ 41,000	[1]
Device Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year	[1]
Device Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year	[1]
Exclusivity Fee [Member]
Revenue, Remaining Performance Obligation, Amount	$ 1,334,000
Exclusivity Fee [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 286,000
Exclusivity Fee [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 286,000
Exclusivity Fee [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 286,000
Exclusivity Fee [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 286,000
Exclusivity Fee [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 190,000
Clinical Revenue [Member]
Revenue, Remaining Performance Obligation, Amount	$ 199,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 13,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 13,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 13,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 13,000
Clinical Revenue [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction (Year)	1 year
Revenue, Remaining Performance Obligation, Amount	$ 147,000

[1] Represents the minimum purchase requirements under the distribution agreement the Company signed with its AXP distributor in China.