3D‐Printed Linear Variable Differential Transformer (LVDT) for Cost‐Effective Displacement Sensing

Abstract

The IoT and Industry 4.0 have increased demand for smart, wireless, customized, and sustainable sensors in industrial environments. Linear Variable Differential Transformers (LVDTs) are crucial for precision displacement sensing due to their high resolution and durability, but face challenges like complex assembly and high manufacturing costs. In this work, a fully printed LVDT position/force sensor is presented, fabricated using fused filament fabrication (FFF) and 5‐axis piezo‐jet printing, enabling the integration of complex geometries and conductive coil patterns directly onto curved surfaces. Two core configurations are evaluated: a commercial MnZn core and a magnetic poly(lactic acid) (PLA) composite core printed via FFF. Electromagnetic and magnetic characterizations revealed that the MnZn core provided superior sensitivity of 1054.3 ± 11.32 µV·mm⁻¹ with respect to the printed core, which exhibited a lower sensitivity of 3.86 ± 0.07 µV·mm⁻¹. The sensors' wireless are integrated with a custom signal conditioning circuit based on the AD598 and an ESP32 microcontroller, allowing real‐time data transmission via Bluetooth Low Energy (BLE). The sensor is implemented in a pressure sensing application, showcasing a linear response with a sensitivity of 3.18 ± 0.22 mV·N⁻¹, offering a highly versatile, scalable, and low‐cost solution for next‐generation industrial sensing in IoT‐enabled environments.