Magnetoresistive Sensors for Microrobotics Using Amorphous Oxide Semiconductors

Oxide semiconductors are pivotal for advancing electronics on non-conventional substrates, including flexible materials and microrobotic platforms. This study introduces Indium Gallium Zinc Oxide (IGZO)-based magnetoresistive (MR) sensors configured in a Wheatstone bridge for magnetic field detection. This is the first demonstration of micromagnet detection using IGZO MR sensors. Commercial MR sensors are often too large for microrobotic integration, necessitating compact, sensitive alternatives. We designed and evaluated two MR element geometries (rectangular and serpentine) to optimize magnetic field sensitivity. The serpentine design <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(1,300\ \mu \mathrm{m} \times\ 1,300\ \mu \mathrm{m})$</tex> achieved a sensitivity of ~ 12.8 mT<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>, surpassing existing IGZO sensors by 463.7 times. Fabrication utilized a low-temperature, scalable process compatible with microrobotics. Experimental results confirmed IGZO's high resistivity (7.95 Ω·cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) and enhanced performance in a Wheatstone bridge configuration. The serpentine sensor exhibited superior sensitivity, offering a compact, high-performance solution for microrobots. This work establishes IGZO MR sensors as a promising avenue for positioning and advanced magnetic sensing in microrobotic applications.