Transcutaneous microvalve activation system using a coreless transformer

Conventional spinal implants show an invariable behavior that is not adapted to patients post-surgery evolution (e.g. scoliosis in children). They work as static and rigid structures that underpin the skeleton. A new visco-elastic spine implant is non-invasively controlled by means of a transcutaneous transformer, for progressive correction of spinal deformities. The bending moment and the torque applied to the spine with this new implant will be externally controlled by activating three intracorporeal microvalves. The power and control signal to activate the appropriated microvalve will be obtained by means of a parallel resonant converter (PRC) with a transcutaneous transformer. Adding a slight oscillation in the frequency control circuit of the power topology, a FM modulation is converted into an AM + FM output modulation on the transcutaneous dc-dc converter. A microcontroller analyses the output voltage envelope of a PRC and activates the corresponding intracorporeal microvalve in a non-intrusive way. Three valves are individually selectable to modify the prosthesis structure although the number of valves can be extended. (C) 2006 Elsevier B.V. All rights reserved.