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Flexible Microsensors based on polysilicon thin film for Monitoring Traumatic Brain Injury (TBI)

Wu, Zhizhen
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045589967871

Abstract Details

2017, PhD, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
Pressure and temperature are parameters essential for brain monitoring. Currently, the intracranial pressure (ICP) and intracranial temperature (ICT) are measured by the separate sensors/catheters in clinic. Although integrated ICP and ICT sensors with low cost and minimal damage to brain is highly favored, the integration of the sensors involves complicate assembly and packaging process, and also increases the diameter of micro-catheters. Researches have been done to develop integrated pressure and temperature sensors on the same platform, especially on flexible substrate, to minimize the damage to brain caused by the device implantation. However, the developed sensors are either merely prove-of-concept or difficult to be manufactured due to the complicate and costly process. This work proposes and explores novel approaches to develop the integrated flexible ICP and ICT sensors with low cost and simple process. High quality polysilicon thin film was directly grown on flexible substrate as the sensing material for both ICP and ICT sensors with simple, fast, and low cost aluminum induced crystallization (AIC) process. A continuous P-type polysilicon film with the crystals’ average size of 49 nm was developed and shown. Based on the polysilicon thin film, a flexible thermistor array was designed, developed and characterized. It achieved good in vitro performance with a sensitivity of -0.0031/°C, response time of 1.5 s, resolution of 0.1 °C, thermal hysteresis less than 0.1°C, and long term stability with drift less than 0.3 °C for 3 days in water. In vivo tests of the polysilicon thermistor showed a low noise level of 0.025±0.03 °C and the expected transient temperature increase associated with cortical spreading depolarization. In addition, polysilicon based flexible pressure sensor was developed for ICP measurement. The gauge factor of polysilicon thin film was characterized with a value of 10.316. The dimensions of the flexible piezoresistive pressure sensor were designed with COMSOL multiphysics simulation to achieve high sensitivity and linearity. The developed flexible pressure sensor showed a sensitivity of 6 × 10-4 / mmHg, resolution of 1 mmHg, and hysteresis of less than 1 mmHg for the pressure range of 10 to 20 mmHg, which totally met the requirements of ICP monitoring. Finally, a 1 × 4 integrated flexible pressure and temperature sensor array was developed and characterized for monitoring the temperature and possible pressure vectors in brain. The real-time measurements of pressure and temperature were performed in an immolated brain model for monitoring any pressure vectors or gradients. The preliminary experiment results showed that the developed sensor array had high enough sensitivity to detect the pressure differences or gradients in brain if any. In conclusion, this work has proposed and developed innovative polysilicon-based flexible temperature and pressure sensors for ICP and ICT monitoring. The development of polysilicon thin film on flexible polyimide with simple, low cost and high yield has been shown. The polysilicon-based temperature and pressure sensors have meet requirements the ICP and ICT monitoring with high sensitivity, high resolution, fast response, and low hysteresis, and can be very beneficial to brain monitoring.
Chong Ahn, Ph.D. (Committee Chair)
Punit Boolchand, Ph.D. (Committee Member)
Leyla Esfandiari, Ph.D. (Committee Member)
Jed Hartings, Ph.D. (Committee Member)
Chunyan Li, Ph.D. (Committee Member)
Ian Papautsky, Ph.D. (Committee Member)
131 p.
Electrical Engineering
Intracranial pressure; Intracranial temperature; flexible sensor; polysilicon thin film; sensor array; MEMS sensor

Recommended Citations

Citations

  • Wu, Z. (2017). Flexible Microsensors based on polysilicon thin film for Monitoring Traumatic Brain Injury (TBI) [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045589967871

    APA Style (7th edition)

  • Wu, Zhizhen. Flexible Microsensors based on polysilicon thin film for Monitoring Traumatic Brain Injury (TBI). 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045589967871.

    MLA Style (8th edition)

  • Wu, Zhizhen. "Flexible Microsensors based on polysilicon thin film for Monitoring Traumatic Brain Injury (TBI)." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1512045589967871

    Chicago Manual of Style (17th edition)

ucin1512045589967871
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© 2017, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.