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Show HTS SQUID ARRAY MAGNETIC FIELD MEASUREMENTS OF PROPAGATING ACTION POTENTIALS IN A FROG SCIATIC Compound action potentials (CAPs) in nerve bundles can be measured by the electromagnetic fields they produce. The frog sciatic nerve provides a useful model for studying the behavior of human nerves because frog nerves are myelinated, as are human nerves. In this experiment, the magnetic field produced by a stimulated frog sciatic nerve bundle was measured using a linear array of four Superconducting Quantum Interference Devices (SQUIDs). A High-Temperature Superconducting (HTS) SQUID was used for the measurements. HTS SQUIDs are somewhat less sensitive than traditional Low-Temperature Superconductor (ITS) SQUIDs, but they are also much safer and more convenient for everyday usage. A NERVE dewar with a ~1 mm liftoff distance was used in conjunction with a specialized nerve chamber to obtain a minimum SQUID liftoff distance and a suitable environment for the nerve bundle. The magnetic field above the nerve bundle was recorded during stimulated CAPs. The averaged magnetic field measurements were compared to the CAP differential voltage recordings at the distal end of the nerve bundle. However, in spite of the small liftoff distance of the array, the resulting magnetic field due to the CAP was found to be too small to recognize the expected signal. Further possible improvements to the method that may help resolve the HTS SQUID signals are discussed. Shawn Forrest Senior Biomedical Engineering shawn@networld.com Faculty Sponsor: Michelle Espy P-21 Biophysics group at Los Alamos National Lab espy@lanl.gov 29 |