Fabrication of Planar Copper Microcoils for Telemetric Orthodontic Applications

The fabrication of electroplated planar copper microcoils for telemetric orthodontic applications is presented. A set of microcoils with overall dimensions of 2 × 2.5 × 0.5 mm3, track widths down to 5 μm and turn numbers up to 35 were fabricated on glass substrates. The coils were electrically characterized and assembled via flip-chip bonding onto a stress-mapping CMOS chip for smart orthodontic brackets. The passive system was successfully read out telemetrically with a reader microcoil for a coil-coil distance of 1 mm at 13.56 MHz. The digital signal representing the measured stress values was extracted telemetrically using a commercially available RFID reader.