Dr. Peter Gruenberg passed away last week; many of you may not recognize the name, but he shared the Nobel-Prize in 2007 with Albert Fert for the independent discoveries they made about an effect called Giant Magnetoresistance (GMR).
This effect identifies tiny charges in a magnetic field that result in huge changes in electrical resistance in the order of 6% and 50% respectively. On the surface, this may not sound so Earth-shaking, but this effect is central to things like tablets and smart phones as well as GPS devices as well as our devices like iPods and MP3 players that store and play the music we so much love.
IBM’s 16.8 Gigabyte hard drive for desktop computers, with their spin valve structure, was a revolutionary development because of GMR.
But there are other, new applications for this technology popping up regularly like the application of GMR in the concept of a sensitive, chip-less, wireless and battery-free current sensor1.
Wireless current sensor design with no ICs and no power supply. The device is composed of a GMR magnetic sensor and a one-port Surface Acoustic Wave (SAW) delay line. (Image courtesy of Reference 1)
The current sensor is designed with a FeMn/NiFe/Cu/NiFe thin-film-based, spin valve meander structured GMR sensor and SAW device transponder integrated using standard microfabrication technology.
I am sure we will see many more applications for GMR devices in the years to come thanks to Gruenberg and Fert.
In 2014, I mention GMR in a Planet Analog article on teleportation: Teleportation, Quantum Mechanics & Quantum Bits
1 TOWARDS A WIRELESS CHIP LESS SMART CURRENT SENSOR SYSTEM BASED ON GIANT MAGNETORESISTANCE Vijay V. Kondalkar, Xiang Li, Sang Sik Yang, and Keekeun Lee, Transducers 2017, Kaohsiung, TAIWAN, June 18-22, 2017