University of California, Davis Davis United States
The major objective was to develop miniaturized, state-of-the-art pressuretemperature sensors to measure TBI impact intracranial pressure ICP combined with longer-term measurements of brain swelling biological ICP and intracranial temperature in animal models of TBI. The goal was to create new sensing technologies by modifying existing contract-stress pressure sensors developed at Lawrence Livermore National Laboratories LLNL. Significant findings include the following. 1 The original LLNL sensors required a sealed reference volume over the sensor diaphragm to reliably detect pressures in a wet environment. 2 Original sensors were modified by epoxying an extremely thin layer of glass over the sensor diaphragm, creating a closed and sealed reference volume. This met with success in measuring TBI impact pressures and accurate temperatures, but lacked sensitivity for measuring the relatively small biological ICP. The increased size of sensor with the glass layer was not ideal. 3 Engineering calculations determined that a thinner diaphragm was necessary to reliably detect pressure changes in the brain swelling range of ICP. 4 The new wafer design and fabrication of the re-engineered sensors has been fraught with technical problems causing unfortunate delays.