Note 4 - Common Stock (Details Textual) - USD ($) | Apr. 26, 2019 | Mar. 31, 2019 | Mar. 26, 2019 | Feb. 28, 2019 | Nov. 30, 2017 | Jun. 30, 2019 | Jun. 30, 2018 | Dec. 31, 2018 |
Common Stock, Shares Authorized | | | | | | 100,000,000 | | 100,000,000 |
Common Stock, Shares Outstanding and Reserved | | | | | | 48,090,748 | | |
Common Stock, Shares, Issued, Total | | | | | | 39,664,199 | | 39,117,524 |
Common Stock, Shares Subscribed but Unissued | | | | | | 2,627,305 | | |
Proceeds from Issuance of Private Placement | | | | | | $ 25,000 | | |
Shares Issued, Price Per Share | $ 0.371 | | | | | | | |
Dividends, Total | | | | | | $ 0 | | |
Finders [Member] | | | | | | | | |
Shares Issued, Price Per Share | | | $ 0.25 | | | | | |
Stock Issued During Period, Shares, Issued for Services | | | 115,000 | | | | | |
Stock Issued During Period, Value, Issued for Services | | | $ 28,750 | | | | | |
Warrant [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 452,617 | | |
Nonqualified Options [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 3,995,000 | | |
Qualified Options [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 950,000 | | |
Private Placement [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 300,000 | | |
Private Placement 2016-2 [Member] | | | | | | | | |
Proceeds from Issuance of Private Placement | | | | | $ 56,225 | | | |
Private Placement 2016-3 [Member] | | | | | | | | |
Stock Issued During Period, Shares, New Issues | | | | 200,000 | | | | |
Shares Issued, Price Per Share | | | | $ 0.25 | | | | |
Officer [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 80,157 | | |
Employees [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 4,294 | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | 4,043 | | | | | | | |
Consultants [Member] | | | | | | | | |
Common Stock, Capital Shares Reserved for Future Issuance | | | | | | 17,176 | | |
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture, Total | | | | 24,000 | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | 16,170 | | | | | | | |
Chief Executive Officer [Member] | | | | | | | | |
Deferred Compensation Arrangement with Individual, Shares Issued | | 100,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | 67,377 | | | | | | | |
Vice President [Member] | | | | | | | | |
Deferred Compensation Arrangement with Individual, Shares Issued | | 12,000 | | | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period | 8,085 | | | | | | | |