Digital SQUID sensors for Low Frequency Imaging Applications

This Small Business Innovation Research Phase I project addresses the development of a magnetic imaging system based on Superconducting QUantum Interference Devices (SQUIDs). SQUIDs are extremely sensitive detectors of magnetic flux and metallic anomalies and, hence, can be used as ultra-sensitive imaging sensors for corrosion detection, as biomagnetometers, and for non-destructive evaluation. The minimum energy sensitivity for SQUIDs is close to h (Planck's constant; 6.6262 x 10-34 J/Hz). A magnetometer based on an array of SQUIDs with sensitivity better than 2 pA/root Hz that requires very simple peripheral electronics has been developed and marketed by HYPRES. However, these DC SQUIDs are incapable of operating in unshielded environments. It is proposed to develop a novel digital SQUID sensor with an integrated pick up loop. This low noise sensor is capable of tracking large signals directly without any pre-filtering, thus allowing the sensor to be operated in a noisy field without magnetic shielding. In the phase I project, an ultra-wide dynamic range digital SQUID chip will be designed, developed, and demonstrated utilizing HYPRES' niobium technology. In the phase II of the program, peripheral electronics will be procured and a complete SQUID-based sensor system will be demonstrated for magnetic imaging and non-destructive evaluation. The funding of this project and its ensuing Phase II program at HYPRES will expedite the development of a system that significantly enhances capabilities in advanced sensor instrumentation.