The objective of this project is to explore the potentials of the internal thermal piezoresistive quality factor and displacement amplification effect in silicon resonant microstructures for realization of ultra-high sensitivity and low noise magnetometers. MEMS magnetometers consisting of silicon based resonant microstructures with integrated insulated metallic traces will be designed and fabricated. The performance of the fabricated devices will be characterized and the effect of internal amplification offered by the strategically designed silicon structure on sensitivity and noise level of the magnetometers will be investigated.
Intellectual Merit: The proposed MEMS magnetometers operate based on harvesting and internally amplifying the Lorentz force (force applied to a current carrying conductor in a magnetic field). Extremely high effective quality factors (Q) up to ~1000X larger than the intrinsic mechanical Q of the resonator have been demonstrated using the internal thermal-piezoresistive amplification effect. It is expected that such high Q values can amplify vibration amplitude resulting from the Lorentz force without adding to the electronic noise level leading to superior performance for the proposed sensors. Preliminary analysis show that noise levels in the pT/Hz1/2 range should be within reach, which is comparable to that offered by some of the most sophisticated technologies available. The proposed effort combines the simplicity, small size, and ease/low cost of fabrication of silicon-based MEMS magnetometers with unprecedentedly high sensitivities. The potential outcome will be small size, low cost and easy to use ultra-sensitive magnetometers that circumvent shortcomings of other existing technologies such as the need for cryogenic cooling, integration of exotic materials, large size and high power consumption.
Broader Impact: Highly sensitive, small size, and easy to use magnetometers can have transformative effects in various areas including biology and biomedical engineering, geology and mineral/oil exploration, as well as surveillance and defense (through wall/underground imaging and target tracking). For example, arrays of SQUIDs requiring cryogenic cooling are currently used for mapping brain activity by monitoring small magnetic fields (tens to thousands of femotTesla) resulting from firing of neurons in the brain. Small size and convenience offered by the proposed microscale devices can leads to significant advances in brain mapping and enable development of advanced portable brain monitoring devices. On the educational front, one postdoctoral researcher, one PhD level graduate student and up to two undergraduate researchers will be trained and directly involved in the research activities. Results from the research activities will serve as interesting course materials enriching the PIs ongoing courses in MEMS and microsystems. The experience gained by the PI during the course of this project will provide him with a highly valuable insight in a new field of research that will be transferred to current and future students.
