Note 7 - Commitments and Contingencies (Details Textual) SFr in Millions	1 Months Ended			12 Months Ended
	Jun. 30, 2018	Aug. 31, 2017 ft²	Feb. 28, 2002	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 CHF (SFr)
Royalty Payment, Percentage of Net Sales			2.50%
Operating Leases, Increase in Office Space | ft²		2,552
Area of Real Estate Property | ft²		7,500
Lessee, Operating Lease, Renewal Term		1 year
Operating Leases, Notice Required to Extend Term		180 days
Operating Leases, Rent Expense				$ 200,000	$ 200,000	$ 200,000
Security Deposit				22,000
Letters of Credit Outstanding, Amount				22,000	14,000
Loans Pledged as Collateral				22,000	$ 14,000
Scenario, Forecast [Member]
Lessee, Operating Lease, Term of Contract	1 year 90 days
Inventories, Four Batches [Member]
Purchase Commitment, Amount Executed				$ 7,800,000			SFr 7.6