Low frequency magnetic fields induced by car tire magnetization.

Alternating magnetic fields have been measured in a variety of different cars, the dominant contribution being from magnetized tires. Magnetic field strengths have been measured as a function of frequency directly at the tires and at different positions in rolling cars. Measurements at the tires showed field strengths up to 100 microtesla (microT). In the interior of rolling cars, close to the wheels at foot regions and at the back seat, field strengths of several microT were obtained in the 10-200 hertz (Hz) frequency domain. In some cases measured field values were considerably higher than those found in previous studies. Purposely magnetizing single tires made it possible to study the influence of various parameters. Degaussed tires retained low field values over prolonged time under conditions of normal use.

Integrating optical fiber force sensors into microforceps for ORL microsurgery.

The delicate anatomy of the ear require surgeons to use great care when operating on its internal structures. One example for such an intervention is the stapedectomy, where a small crook shaped piston is placed in the oval window of the cochlea and connected to the incus through crimping thus bypassing the diseased stapes. Performing the crimp process with the correct force is necessary since loose crimps poorly transmit sound whereas tight crimps will eventually result in necrosis of the incus. Clinically, demand is high to reproducibly conduct the crimp process through a precise force measurement. For this reason, we have developed a fiber Bragg grating (FBG) integrated microforceps for use in such interventions. This device was calibrated, and tested in cadaver preparations. With this instrument we were able to measure for the first time forces involved in crimping a stapes prosthesis to the incus. We also discuss a method of attaching and actuating such forceps in conjunction with a robot currently under development in our group. Each component of this system can be used separately or combined to improve surgical accuracy, confidence and outcome.