Note 3 - Stockholders' Equity (Tables)
|
6 Months Ended |
Jun. 30, 2026 |
|---|
| Notes Tables |
|
| Schedule of Stock Options Roll Forward [Table Text Block] |
| | | | | | | Weighted | |
| | | | | | | Average | |
| | | Number of | | | exercise | |
| | | shares | | | price | |
| | | | | | | US$ | |
| Outstanding, December 31, 2025 | | | 29,681,325 | | | | 0.20 | |
| | | | | | | | | |
| Changes during 2026: | | | | | | | | |
| Granted to employees, officers, directors and others | | | 200,000 | | | | 0.21 | |
| Expired/Cancelled/Forfeited | | | (325,000 | ) | | | 0.59 | |
| Exercised | | | (600,000 | ) | | | 0.11 | |
| Outstanding, June 30, 2026 | | | 28,956,325 | | | | 0.19 | |
| Exercisable, June 30, 2026 | | | 28,956,325 | | | | 0.19 | |
|
| Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block] |
| Shares underlying outstanding options (fully vested) | |
| | | | | | | | Weighted | | | | | |
| | | | | | | | average | | | Weighted | |
| Range of | | | | | | | remaining | | | Average | |
| exercise | | | Number | | | contractual | | | Exercise | |
| price | | | outstanding | | | life (years) | | | price | |
| US$ | | | | | | | | | | | US$ | |
| 0.01 | | | | 107,500 | | | | 0.50 | | | | 0.01 | |
| 0.01 | | | | 40,000 | | | | 0.80 | | | | 0.01 | |
| 0.01 | | | | 40,000 | | | | 1.25 | | | | 0.01 | |
| 0.01 | | | | 62,500 | | | | 1.50 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 1.51 | | | | 0.01 | |
| 0.01 | | | | 30,000 | | | | 1.66 | | | | 0.01 | |
| 0.01 | | | | 4,000 | | | | 1.77 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 2.52 | | | | 0.01 | |
| 0.01 | | | | 35,000 | | | | 3.22 | | | | 0.01 | |
| 0.01 | | | | 150,000 | | | | 3.39 | | | | 0.01 | |
| 0.01 | | | | 35,000 | | | | 3.52 | | | | 0.01 | |
| 0.01 | | | | 75,000 | | | | 4.52 | | | | 0.01 | |
| 0.01 | | | | 200,000 | | | | 4.89 | | | | 0.01 | |
| 0.01 | | | | 200,000 | | | | 5.05 | | | | 0.01 | |
| 0.01 | | | | 10,000 | | | | 5.17 | | | | 0.01 | |
| 0.01 | | | | 300,000 | | | | 5.52 | | | | 0.01 | |
| 0.01 | | | | 55,000 | | | | 5.55 | | | | 0.01 | |
| 0.01 | | | | 560,000 | | | | 5.80 | | | | 0.01 | |
| 0.01 | | | | 75,000 | | | | 6.12 | | | | 0.01 | |
| 0.01 | | | | 10,000 | | | | 6.18 | | | | 0.01 | |
| 0.01 | | | | 495,000 | | | | 6.24 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 6.52 | | | | 0.01 | |
| 0.01 | | | | 10,000 | | | | 7.18 | | | | 0.01 | |
| 0.01 | | | | 895,000 | | | | 7.23 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 7.52 | | | | 0.01 | |
| 0.01 | | | | 10,000 | | | | 8.18 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 8.52 | | | | 0.01 | |
| 0.01 | | | | 10,000 | | | | 9.18 | | | | 0.01 | |
| 0.01 | | | | 25,000 | | | | 9.52 | | | | 0.01 | |
| 0.06 | | | | 50,000 | | | | 6.52 | | | | 0.06 | |
| 0.07 | | | | 125,000 | | | | 7.52 | | | | 0.07 | |
| 0.07 | | | | 5,837,000 | | | | 7.24 | | | | 0.07 | |
| 0.10 | | | | 175,000 | | | | 8.52 | | | | 0.10 | |
| 0.14 | | | | 210,000 | | | | 5.55 | | | | 0.14 | |
| 0.15 | | | | 2,900,000 | | | | 5.52 | | | | 0.15 | |
| 0.15 | | | | 5,854,325 | | | | 5.80 | | | | 0.15 | |
| 0.16 | | | | 75,000 | | | | 3.45 | | | | 0.16 | |
| 0.18 | | | | 4,730,000 | | | | 6.24 | | | | 0.18 | |
| 0.24 | | | | 25,000 | | | | 6.09 | | | | 0.24 | |
| 0.24 | | | | 118,000 | | | | 6.12 | | | | 0.24 | |
| 0.24 | | | | 175,000 | | | | 9.52 | | | | 0.24 | |
| 0.25 | | | | 50,000 | | | | 5.17 | | | | 0.25 | |
| 0.25 | | | | 363,000 | | | | 5.17 | | | | 0.25 | |
| 0.28 | | | | 25,000 | | | | 3.18 | | | | 0.28 | |
| 0.29 | | | | 25,000 | | | | 0.96 | | | | 0.29 | |
| 0.39 | | | | 1,260,000 | | | | 5.03 | | | | 0.39 | |
| 0.59 | | | | 1,200,000 | | | | 0.89 | | | | 0.59 | |
| 0.59 | | | | 1,400,000 | | | | 4.89 | | | | 0.59 | |
| 0.92 | | | | 300,000 | | | | 0.51 | | | | 0.92 | |
| 0.92 | | | | 500,000 | | | | 4.52 | | | | 0.92 | |
| 0.01 - 0.92 | | | | 28,956,325 | | | | | | | | 0.19 | |
|
| Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
| | | For the Six Months Ended | |
| | | June 30, | |
| | | 2026 | | | 2025 | |
| Weighted-average fair value of underlying stock at grant date | | $ | 0.24 | | | $ | 0.10 | |
| Dividend yields | | | — | | | | — | |
| Expected volatility | | | 126 | % | | | 135 | % |
| Risk-free interest rates | | | 3.71 | % | | | 4.41 | % |
| Expected lives (in years) | | | 5.00 | | | | 5.00 | |
| Weighted-average grant date fair value | | $ | 0.21 | | | $ | 0.09 | |
|
| Share-Based Payment Arrangement, Cost by Plan [Table Text Block] |
| For the Three Months Ended June 30, | |
| 2026 | | | 2025 | |
| US$ thousands | | | US$ thousands | |
| — | | | | — | |
| For the Six Months Ended June 30, | |
| 2026 | | | 2025 | |
| US$ thousands | | | US$ thousands | |
| 42 | | | | 18 | |
|
| Share-Based Payment Arrangement, Activity [Table Text Block] |
| | | | | | Warrant | | Outstanding | | | | | | | | | | | | | | | Outstanding | |
| | | Exercise | | Termination | | Balance, | | | Warrants | | | Warrants | | | Warrants | | | Balance, | |
| Warrants | | Price | | Date | | 12/31/2025 | | | Issued | | | Exercised | | | Expired | | | 06/30/2026 | |
| ZNWAA | | $ | 2.00 | | 01/31/2031 | | | 1,498,804 | | | | - | | | | - | | | | - | | | | 1,498,804 | |
| ZNWAS | | $ | 0.25 | | 10/15/2026 | | | - | | | | 145,180,117 | | | | - | | | | - | | | | 145,180,117 | |
| ZNWAT | | $ | 0.18 | | 08/31/2026 | | | 9,019,652 | | | | - | | | | - | | | | - | | | | 9,019,652 | |
| ZNWAU | | $ | 0.25 | | 10/15/2026 | | | - | | | | 19,147,462 | | | | - | | | | - | | | | 19,147,462 | |
| ZNWBA | | $ | 0.25 | | 03/31/2026 | | | 1,177,950 | | | | - | | | | (396,890 | ) | | | (781,060 | ) | | | - | |
| ZNWBB | | $ | 0.25 | | 10/15/2026 | | | 15,000,000 | | | | - | | | | - | | | | - | | | | 15,000,000 | |
| Outstanding warrants | | | | | | | | 26,696,406 | | | | 164,327,579 | | | | (396,890 | ) | | | (781,060 | ) | | | 189,846,035 | |
| | | Period of Grant | | US$ | | Expiration Date |
| ZNWAA Warrants | A,B,C,D,F,I | March 2013 – December 2014 | | | 2.00 | | January 31, 2031 |
| ZNWAS Warrants | E,N | August 2021 – March 2022 | | | 0.25 | | October 15, 2026 |
| ZNWAT Warrants | H,J,L,M,O,P,Q | August – September 2022 | | | 0.18 | | August 31, 2026 |
| ZNWAU Warrants | E,N | October – November 2022 | | | 0.25 | | October 15, 2026 |
| ZNWBB Warrants | G,K,N | April 2024 – June 2025 | | | 0.25 | | October 15, 2026 |
|