SBIR Phase II: Flux-Gated Spin-Dependent-Tunneling Sensors

This Small Business Innovation Research Phase II project seeks to fabricate a novel nanotechnology spin-dependent tunneling (SDT) magnetic field sensor device with increased signal-to-noise performance at low frequencies. The increased resolution at low frequencies is greatly desired in a large number of application markets. The proposed device is based on innovative methods of modulating the permeability of, and/or the flux through, integrated flux concentrators. These methods of "flux gating" (chopping or sweeping the magnetic field which is sensed by the SDT transducers) are employed using on-chip, microfabricated coil structures. The project explores the nature of frequency-dependent (or 1/f) noise that is intrinsic to SDT devices, and offers an integrated low-power method of noise reduction. SDT technology is at the leading edge of magnetoresistive transducer development due, in part, to the fact that its magnetoresistance can be more than 3 times that of the best giant magnetoresistive devices, and more than 15 times that of the anisotropic magnetoresistive sensors on the market today. The devices for this Phase II is based on novel and proprietary concepts for the advancement of small, solid-state, low-cost, low-power magnetic field sensors. The primary need is for high-resolution magnetic field sensors that are more fieldable and cost effective. SDT technology offers this high-resolution potential as well as the low-cost advantages of silicon fabrication methods used for SDT micro-sensors. Applications for these sensors include non-destructive testing, security and surveillance, and magnetic media validation. Each of these very diverse applications share a common need for the small, highly sensitive, low power magnetic field sensing devices being proposed. The new devices will enable each of these areas to expand into small portable applications and into areas where cost effective low-field sensing has not been possible.