# Contactless Inductive Sensors Using Glass-Coated Microwires

## TL;DR

This paper explores how glass-coated microwires can be used as contactless sensors by tuning their magnetic properties for various sensing applications.

## Contribution

The paper compares two novel contactless readout methodologies for microwire sensors for the first time.

## Key findings

- Microwire magnetic properties can be tuned via composition and annealing to achieve nonlinear magnetization.
- Contactless sensors for stress, pressure, temperature, and magnetic particles are enabled by these properties.
- Time-domain and frequency-domain readout methods are effective for sensor output.

## Abstract

What are the main findings?
Tunability of magnetic properties of amorphous microwires by composition and annealing helps to realize a specific nonlinear magnetization response.The extent and nature of magnetic nonlinearity is controlled through external stimuli.

Tunability of magnetic properties of amorphous microwires by composition and annealing helps to realize a specific nonlinear magnetization response.

The extent and nature of magnetic nonlinearity is controlled through external stimuli.

What are the implications of the main findings?
Amorphous and nanocrystalline microwires are used for contactless sensors based on nonlinear magnetization dynamics.Two key contactless readout methodologies: time-domain detection of the switching field for bistable wires and frequency-domain harmonic analysis are used for sensor output.Contactless mechanical stress, pressure, temperature sensors and magnetic particle detection are discussed.

Amorphous and nanocrystalline microwires are used for contactless sensors based on nonlinear magnetization dynamics.

Two key contactless readout methodologies: time-domain detection of the switching field for bistable wires and frequency-domain harmonic analysis are used for sensor output.

Contactless mechanical stress, pressure, temperature sensors and magnetic particle detection are discussed.

This paper explores the potential of amorphous and nanocrystalline glass-coated microwires as highly versatile, miniaturized sensing elements, leveraging their intrinsic nonlinear magnetization dynamics. In magnetic systems, this approach is particularly advantageous because the degree of nonlinearity can be externally tuned using stimuli such as applied magnetic fields, mechanical stress, or temperature variations. From this context, we summarize key properties of microwires—including bistability, a specific easy magnetization direction, internal stress distributions, and magnetostriction—that can be tailored through composition and annealing. In this review, we compare for the first time two key contactless readout methodologies: (i) time-domain detection of the switching field and (ii) frequency-domain harmonic analysis of the induced voltage. These principles have been successfully applied to a broad range of practical sensors, including devices for monitoring mechanical stress in structural materials, measuring temperature in biomedical settings, and detecting magnetic particles. Together, these advances highlight the potential of microwires for embedded, wireless sensing in both engineering and medical applications.