Patents
| US Patent # | Date Issued | |
| 1. | 4,738,623 | April 19, 1988 |
| 2. | 5,484,285 | January 16, 1996 |
| 3. | 5,499,918 | March 19, 1996 |
| 4. | 5,749,731 | May 12, 1998 |
| 5. | 5,827,062 | October 27, 1998 |
| 6. | 5,888,066 | March 30, 1999 |
| 7. | 6,200,345 | March 13, 2001 |
| 8. | 6,227,857 | May 8, 2001 |
| 9. | 6,290,500 | September 18, 2001 |
| 10. | 6,325,628 | December 4, 2001 |
| 11. | 6,592,370 | July 15, 2003 |
| 12. | 6,688,887 | February 10, 2004 |
| 13. | 6,991,462 | January 31, 2006 |