Note 5 - Share-based Compensation - Stock Compensation Expense (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
|
Stock compensation expense | $ 383,140 | $ 313,943 | $ 1,130,945 | $ 957,711 |
Research and Development Expense [Member] | ||||
Stock compensation expense | 64,970 | 59,434 | 195,316 | 177,514 |
Selling and Marketing Expense [Member] | ||||
Stock compensation expense | 64,152 | 55,402 | 201,907 | 173,072 |
General and Administrative Expense [Member] | ||||
Stock compensation expense | 194,764 | 156,621 | 576,718 | 479,803 |
Cost of Sales [Member] | ||||
Stock compensation expense | $ 59,254 | $ 42,486 | $ 157,004 | $ 127,322 |