MR damper 'naturalizes' prosthetic leg

Schwenningen, Germany -Negotiating slopes and stairs is no easy task for persons who use a prosthetic leg. Conventional stepper motor-powered prosthetic devices lack the stability and responsiveness of the natural leg's knee and muscles.

Biedermann Motech GmbH, a manufacturer of spinal implants and prosthetic components, along with Lord Corp., a materials technology company, may change this situation. Together, the two companies have produced a prosthetic device that they claim drastically improves the mobility of leg amputees by more closely recreating a natural gait.

Battery-operated and electronically controlled, Motech's "Smart Magnetix" system combines electronics and software, with controllable magneto-rheological (MR) fluid technology. MR materials, when exposed to a magnetic field, change consistency from a fluid state to a near-solid state. Micron-sized particles, dispersed in a carrier medium, respond to an applied magnetic field within milliseconds, allowing for real-time control of the fluid rheology.

Conventional hydraulic shocks are not real time adjustable, and controllable hydraulic shocks with stepper motors to adjust the valving offer less speed and control, says Lutz Biedermann, president of Biedermann Motech. In contrast, the Smart Magnetix system continually calculates changes in uphill and downhill motion, walking speed, and load to adjust to ramps, stairs, and terrain variations. Response is said to be 20xfaster than state-of-the-art.

"Lord's controllable material," says Biedermann, "has made it possible for patients to achieve confidence in their steps for an improved quality of life."