Millions of Hall devices are manufactured each year for use in contactless sensing. These sensors are empowering green transport as part of brushless electric motors in aircraft and in electric cars, for example, and are important in anti-lock braking systems and electronic compasses. To expand future applications, their performance needs to be improved.

Today's Hall devices can be rendered ineffective for sensing by an offset voltage problem. This is a spurious voltage — caused by factors such as contact misalignment — that appears across the Hall contacts even in the absence of a magnetic field. It has long been known that a sign-reversed Hall voltage can be produced when a Hall device that contains an interior void is turned inside-out with respect to the magnetic field (R. G. Mani and K. von Klitzing Appl. Phys. Lett. 64, 1262–1264; 1994; see also M. Briane and G. Milton Arch. Rational Mech. Anal. 193, 715–736; 2009 and C. Kern et al. Phys. Rev. Lett. 118, 016601; 2017). This phenomenon is useful for engineering the distribution of current so as to reduce offset voltages, increasing magnetic-field sensitivity.

An industrial partner will be needed to integrate these concepts into the technology of silicon electronics to realize a better, low-cost, smart Hall sensor for the mass market.