Sensitive MEMS-based Gradiometer

Heart disease is the leading cause of death for Americans, an estimated 6.1 million of which suffer from heart arrhythmias. Detection methods are scarce and expensive, leaving many undetected and unmonitored in the event of severe palpitation. The gold standard detection is the electrocardiogram, which is not available for continuous monitoring and is susceptible to conductive tissue noise and signal attenuation. A competing technology, magnetocardiography, has resurfaced due recent technological advances, which remain hampered by large expense and shielding requirements. To fill the fill this void, we present a pT/cm sensitive, inexpensive magnetometer leveraging decades of engineering in commercially available MEMS technology. Weak electromagnetic signals are detected by mechanically coupling a commercially available, micro-sized, permanent magnet with the proof mass of a capacitive accelerometer, which is highly engineered to sense pN forces. By design, our device measures gradient fields directly and rejects time-varying bias fields. An affordable, real-time cardiac monitoring system could have a profound impact on an otherwise unmonitored field of cardiac disease.