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Author: | Song, Jinsong |
Title: | On Optimization and Read-out Resolution of the Zero Power Sensor |
Publication type: | Master's thesis |
Publication year: | 2012 |
Pages: | [8] + 59 Language: eng |
Department/School: | Radiotieteen ja -tekniikan laitos |
Main subject: | Radiotekniikka (S-26) |
Supervisor: | Räisänen, Antti |
Instructor: | Viikari, Ville |
Electronic version URL: | http://urn.fi/URN:NBN:fi:aalto-201212083432 |
OEVS: | Electronic archive copy is available via Aalto Thesis Database.
Instructions Reading digital theses in the closed network of the Aalto University Harald Herlin Learning CentreIn the closed network of Learning Centre you can read digital and digitized theses not available in the open network. The Learning Centre contact details and opening hours: https://learningcentre.aalto.fi/en/harald-herlin-learning-centre/ You can read theses on the Learning Centre customer computers, which are available on all floors.
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Location: | P1 Ark Aalto 813 | Archive |
Keywords: | conjugate matching intermodulation response mixers RFID read-out resolution sensitivity wireless sensor |
Abstract (eng): | Wireless sensors are emerging these days. In certain applications, they reduce installation complexity and maintenance costs. However, there are still limitations with the current passive wireless sensors such as a short detection distance and limited parameters to monitor. In this thesis work, we further develop a new concept called Zero Power to overcome challenges related to the state-of-art of passive wireless sensors. Zero Power sensor is claimed to exhibit a long read-out distance and being capable to monitor several quantities. The concept utilizes the intermodulation communication principle, in which the sensor rejects a signal which contains sensing information at the intermodulation frequency while illuminated by the reader device at two closely located frequencies. A wired sensor prototype is fabricated. The sensitivity of the sensor is experimentally characterized and the achievable read-out resolution, which defines the smallest detectable relative change in the sensor capacitance, is theoretically predicted for the first time. After the first prototype, the optimization theory of the sensor circuit is established. Based on the theory, the sensor circuit is optimized to achieve the best resolution. A conjugate matched antenna for the sensor is utilized to reduce the complexity of the sensor circuit and the energy consumption. An optimized sensor with an antenna is manufactured. The sensitivity of the optimized sensor is experimentally characterized and the achievable read-out resolution of the optimized sensor is estimated. Finally, a wireless ECG (Electrocardiography) measurement is demonstrated with the optimized sensor. According to the experimental results, the sensor can offer 1 % relative resolution (1 % change in the sensor capacitance can be detected) at 13 m distance. |
ED: | 2012-11-23 |
INSSI record number: 45430
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