Nanoscale SQUIDs for a closer look at brain functions
By Thilo Bauch, Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Sweden
The seminar will take place in a hybrid format at ESPCI, Room Charpak, building C, 2nd floor.
Recent advances in nano-patterning of high critical-temperature (high-Tc) superconductors have led to simpler, more flexible, and highly sensitive superconducting quantum interference device (SQUID) magnetometers compared to existing technologies. Current approaches, bicrystals and step-edges, dating back to the 1980s, require complex multilayer configurations, limiting sensitivity and design options. Our innovative grooved Dayem-bridges process overcomes these challenges, achieving or surpassing low-noise performance while using a single high-Tc film. This streamlined fabrication allows for unprecedented design flexibility and scalable production of advanced magnetometer systems for applications in non-destructive evaluation, geomagnetism, and biomagnetism, notably in medical imaging like magnetoencephalography (MEG).
Our SQUIDs operate at a moderate temperature (~77 K), enabling close proximity (within 1 mm) to the head surface where stronger neuromagnetic signals are generated, enhancing imaging resolution. In contrast, current MEG systems rely on low-Tc SQUIDs, necessitating extreme cryogenic temperatures (~4 K) and substantial liquid helium consumption. By densely placing our highly sensitive magnetometers around the scalp, we anticipate detecting stronger signals with improved spatial sampling. Additionally, we can transition from costly liquid helium to more accessible liquid nitrogen, revolutionizing neuroimaging capabilities at a reduced cost compared to the state-of-the-art.
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