High-performance sensing in a compact footprint

In complex actuators, such as those used in robotics, sensors must capture motion and condition data in a confined space. Conventional magnetic sensor systems often consist of a sensor chip and a separately mounted permanent magnet. This arrangement takes up considerable space and makes it difficult to align the components precisely with one another. Reducing the size of the magnets, in turn, may require significant amounts of rare-earth materials or compromise measurement performance.

MicroBias addresses these challenges by integrating the permanent magnet as a micromagnet directly into the silicon substrate of the sensor chip at wafer level. The magnet and sensing elements are positioned relative to one another with submicrometer precision, allowing the local magnetic field to be tailored to the specific sensing task and mechanical requirements. Together with integrated signal processing, this creates a fully integrated, monolithic sensor system without compromising performance, as the extremely small distance between the sensor and magnet ensures excellent signal quality. In this so-called back-bias system, the integrated magnet generates a bias field that enables the sensor to detect the motion or condition of an external component. Compared with conventional sensor-magnet assemblies offering the same measurement performance, this makes it possible to reduce the sensor-magnet volume by  a factor of up to 100 and use up to 99 percent less rare-earth magnet material. A specific comparison illustrates the scale of this reduction: The magnet in a comparable back-bias system has a volume of 30 cubic millimeters, whereas a single micromagnet has a volume of around 0.03 cubic millimeters. Even if ten such micromagnets are combined to achieve the same measurement performance, their combined magnet volume is only one hundredth that of the magnet in the conventional system.

Tailored sensor solutions for demanding applications

One potential application for the sensor chip is robot joints: MicroBias can integrate the sensing technology required to detect joint movements directly into the robot joint, eliminating the need for additional magnets and saving valuable space. This leaves more space for the drive and mechanical components, enabling new approaches to the design of compact robot joints. Other potential applications include gripper systems, tactile and switching sensors, and hard-to-access machine components where precise motion and condition sensing is required in confined spaces.

Based on MicroBias, Fraunhofer IIS develops application-specific sensor solutions, combining its expertise in multidimensional magnetic field sensing, circuit design and intelligent algorithms. The technology is already available for 3D Hall sensing and can be adapted for use with magnetoresistive sensors through joint development projects. The range of services extends from feasibility studies and magnetic system design through modeling and simulation to the development and validation of system prototypes. In implementing the technology, Fraunhofer IIS cooperates with Fraunhofer ISIT, which contributes its PowderMEMS technology for wafer-level micromagnet integration designed for volume production, and Fraunhofer IFAM, which contributes its expertise in materials processing.

Discover MicroBias at electronica 2026

From November 10 to 13, 2026, Fraunhofer IIS will showcase MicroBias at electronica in Munich. Manufacturers of magnetic field sensors and sensor modules, companies in the robotics, mechanical engineering and automation sectors, and system integrators, can talk to Fraunhofer IIS experts in Hall C5, Booth 241 to discuss MicroBias and its potential applications and development opportunities.