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Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	May 31, 2018
Provision for Doubtful Accounts		$ 20	$ 68
Inventory Write-down		285	251
Depreciation, Total		768	618
Contingent Liability, Repayment of State and Local Grant Funds Received		200
Foreign Currency Transaction Gain (Loss), before Tax, Total		$ (165)	$ 146
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	35.00%
Accrued Rent, Current		$ 380	$ 521
Subsequent Event [Member] \| Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 4,873
Other Current Liabilities [Member]
Accrued Rent, Current		$ 380
City of Rochester and State of New York [Member]
Grants Receivable					$ 550
Minimum [Member]
Property, Plant and Equipment, Useful Life		1 year
Maximum [Member]
Property, Plant and Equipment, Useful Life		10 years
Thermal Products and Mechanical Products [Member]
Equipment Leased To Customers Initial Term	180 days