Note 1 - Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2021

Notes Tables

Property Plant and Equipment Useful Life [Table Text Block]

	Years
Computers, software and office equipment	3	-	10
Leasehold improvements (1)	2	-	5
Manufacturing tooling	3	-	7
Laboratory equipment	4	-	6
Demo equipment		3

Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]

	For the six months ended June 30,
	2021			2020
	Stock Options
Expected dividend yield		0.0%			0.0%
Expected stock price volatility	84.8%	-	89.6%	82.6%	-	86.8%
Risk-free interest rate	0.93%	-	1.45%	0.62%	-	1.78%
Expected life (in years)		10			10
	Warrants
Expected dividend yield		0.0%			0.0%
Expected stock price volatility	84.8%	-	89.6%	82.6%	-	86.8%
Risk-free interest rate	0.42%	-	1.04%	0.33%	-	0.79%
Expected life (in years)	3	-	5.5	2	-	5.5