Researchers Develop Low-Cost 2D Magnetic Sensors That Operate in Adverse Conditions

A research team from the Fraunhofer Institute for Electronic Nano Systems (ENAS) has developed a new method of manufacturing 2D magnetic sensors, which reduces the cost and production time by half.

Magnetic sensors are suitable for harsh operating conditions and fluid measurements. Therefore, they are usually preferred in environments where other measurement techniques fail to produce results.

Ideal examples of magnetic sensors are navigation devices that indicate the appropriate direction even before the car starts. Smart phones have different map applications that make use of magnetic sensors to show the right direction. The sensor determines the position of the device with respect to the magnetic field of the earth.

Inexpensive one-dimensional sensors are commonly used in various applications. However, these sensors are insensitive and inaccurate when compared to the 2D models. The compact two-dimensional sensors hold promise for smart phone applications. The researchers have optimized the 2D magnetic sensor manufacturing process. Dr. Olaf Ueberschär, group manager at the ENAS said that, "The costs and manufacturing time for two-dimensional magnetic field sensors drop by half".

The scientists employed only one piece of fundamental material required for producing sensors, which substantially reduced the production cost of these 2D sensors. One-dimensional sensors usually require two microelectronic half-bridges with applied magnetic fields pointing away from each other. Two different material pieces have to be joined for any magnetic material to exhibit its magnetization direction, i.e. alignment of the magnetic field within them. This is an intricate and expensive process. 2D sensors were produced using two half-bridge sensors or four pieces of material.

Ueberschär claimed that, "For the first time we are able to produce not only the full bridges, but also the two-dimensional sensors monolithically – from one piece".

The researchers produced the sensors by separating a material layer from a wafer, and etching it to achieve the desired structure. Following this, they carried out a laser treatment, which enabled them to bring out the preferred magnetic directions in the 2D sensors.

Another benefit of these models is their size. The new 2D sensors are nearly half the size of the previous models, accounting to less than a square millimeter. With smaller sizes, the mini-chips can be used for various applications. For instance, to achieve high resolution in the magnetic field cameras carrying number of sensors in different columns and lines, the size of the sensors should be as small as possible to ensure a closer arrangement without any mutual interference.

Apart from in smart phones, magnetic sensors are also applied in adverse operating conditions such as hot oil baths and fluids. They are also employed in fully electronic gear levers installed on the steering wheel or the center console in automobiles. Other applications include medical diagnostics to identify and locate viruses, bacteria and other tropical diseases.

The prototypes of the two-dimensional sensors will be presented at the Sensor + Test trade fair that is likely to be held from May 19 to 21, 2015 in Nuremberg. However, commercialization of the product might take approximately a year.