Exploration of a PEALD platinum thermal accelerometer
Abstract/Contents
- Abstract
- The use of microelectromechanical systems (MEMS) inertial sensors for high-bandwidth applications in extreme environments has proved challenging due to inherent limitations imposed by the governing physics and the available sensing mechanisms. Thermal accelerometers rely on an entirely different set of physics and thus are not subject to these same limitations. This thesis presents a thermal accelerometer fabricated with plasma enhanced atomic layer deposition (PEALD). The deposition of thinner Pt films enabled by PEALD allows for decreased parasitic heat pathways, and correspondingly decreased thermal time constants, relative to previous thermal accelerometers. This work first describes the fabrication process for these devices and demonstrates the long-term resistance stability of the individual suspended films. Confirming the film stability represented an important initial step, as such films have had very limited use in sensor applications and thus have not undergone extensive electrical stability validation. Next, the initial performance metrics of our device are investigated. Results show a sensitivity of 0.149 C/g and a noise of 22.5 mg for a heater temperature rise of 290 C. With the addition of a temperature compensation scheme based on the common mode sensor resistances, the device showed no temperature sensitivity. Finally, this work explores several modulated operating modes. Modulating the heater was shown to reduce long term drift by half, whereas modulating the bridge reduced the noise density by about 20%. However, pure AC heating is subject to a extra trade-off between sensitivity and bandwidth: the sensitivity declines for heating frequencies higher than the full system cutoff frequency (which, as it includes the time for the heater to Joule heat, has a longer time constant and thus a lower cutoff frequency than for acceleration), and the chosen heating frequency ultimately defines the ceiling for the potential system bandwidth to acceleration. Pulsed heating offers an alternative modulated heating scheme with the same reduced drift benefits. This pulsed scheme may better optimize for both low noise and low drift without the corresponding bandwidth limitations.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Kaplan, Kirsten Elana |
|---|---|
| Degree supervisor | Kenny, Thomas William |
| Thesis advisor | Kenny, Thomas William |
| Thesis advisor | Howe, Roger Thomas |
| Thesis advisor | Prinz, F. B |
| Degree committee member | Howe, Roger Thomas |
| Degree committee member | Prinz, F. B |
| Associated with | Stanford University, Department of Mechanical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Kirsten Elana Kaplan. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Kirsten Elana Kaplan
- License
- This work is licensed under a Creative Commons Attribution Non Commercial Share Alike 3.0 Unported license (CC BY-NC-SA).
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