Wireless control of small electronic tags using air-coupled ultrasound
Abstract/Contents
- Abstract
- In the more than 130 years since the first experimental confirmation of radiofrequency (RF) electromagnetic waves, RF waves have been used with increasing effectiveness to improve wireless connectivity. In fact, the total number of wirelessly connected devices is now greater than the total human population, suggesting that people-to-people connectivity is no longer the chief driver of advances in wireless systems. Instead, there is now an assortment of niche applications that, when combined, are going to be increasingly important if the upward trend in the number of wireless systems is to continue into the trillions of devices. To enable this trend to continue, the design of wireless devices will need to be fundamentally rethought; there will need to be a new class of devices that are centimeter-sized or smaller, wirelessly controlled, and either rechargeable or battery-free. In this work, we present the use of air-coupled ultrasound for the control of small wireless devices that meet the criteria given above. The primary advantages of ultrasound over RF derive from its low wave speed in air (allowing operation at low frequencies and small wavelengths simultaneously), while secondary advantages stem from how the emission of ultrasound is regulated (a single intensity limit without transmitter power or gain restrictions). We describe three proof-of-concept projects in which we have leveraged these advantages to build state-of-the-art wireless systems. Common to these projects is the use of a millimeter-sized charge-biased ultrasonic transducer first reported in 2012 that allows for self-sufficient high-sensitivity operation in a small form factor. The first project we describe is an exploration of ultrasonic wireless power delivery to millimeter-sized tags. Our simulation-based case study, validated by measurements of wireless power recovery, shows that ultrasound is effective for transferring small amounts of power to small tags out to several meters away from a reader. Next, we detail the design of our ultrasonic wake-up receiver, which leverages a custom CMOS chip to achieve competitive sensitivity and power consumption while having the smallest footprint among all published RF and acoustic solutions. Finally, we present our work on the combined use of RF and ultrasound for the localization of small, battery-free tags; measurements with a proof-of-concept system show sub-decimeter accuracy out to several meters away from a reader, with future work predicted to achieve sub-cm accuracy for cm-sized tags over the same range. Overall, this work demonstrates that air-coupled ultrasound can be effectively harnessed to move toward a trillion-device reality.
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 | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Rekhi, Angad Singh |
|---|---|
| Degree supervisor | Arbabian, Amin |
| Thesis advisor | Arbabian, Amin |
| Thesis advisor | Khuri-Yakub, Butrus T, 1948- |
| Thesis advisor | Lee, Thomas H, 1959- |
| Degree committee member | Khuri-Yakub, Butrus T, 1948- |
| Degree committee member | Lee, Thomas H, 1959- |
| Associated with | Stanford University, Department of Electrical Engineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Angad Singh Rekhi. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2020. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Angad Singh Rekhi
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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