A thermally powered ISFET array for on-body pH measurement
File(s)
Accepted version
Author(s)
Douthwaite, Matthew
Koutsos, Ermis
Yates, David C
Mitcheson, Paul D
Georgiou, Pantelis
Type
Journal Article
Abstract
Recent advances in electronics and electrochemical sensors have led to an emerging class of next generation wearables, detecting analytes in biofluids such as perspiration. Most of these devices utilize ion-selective electrodes (ISEs) as a detection method; however, ion-sensitive field-effect transistors (ISFETs) offer a solution with improved integration and a low power consumption. This work presents a wearable, thermoelectrically powered system composed of an application-specific integrated circuit (ASIC), two commercial power management integrated circuits and a network of commercial thermoelectric generators (TEGs). The ASIC is fabricated in 0.35 μm CMOS and contains an ISFET array designed to read pH as a current, a processing module which averages the signal to reduce noise and encodes it into a frequency, and a transmitter. The output frequency has a measured sensitivity of 6 to 8 kHz/pH for a pH range of 7-5. It is shown that the sensing array and processing module has a power consumption 6 μW and, therefore, can be entirely powered by body heat using a TEG. Array averaging is shown to reduce noise at these low power levels to 104 μV (input referred integrated noise), reducing the minimum detectable limit of the ASIC to 0.008 pH units. The work forms the foundation and proves the feasibility of battery-less, on-body electrochemical for perspiration analysis in sports science and healthcare applications.
Date Issued
2017-12-01
Date Acceptance
2017-07-02
Citation
IEEE Transactions on Biomedical Circuits and Systems, 2017, 11 (6), pp.1324-1334
ISSN
1932-4545
Publisher
Institute of Electrical and Electronics Engineers
Start Page
1324
End Page
1334
Journal / Book Title
IEEE Transactions on Biomedical Circuits and Systems
Volume
11
Issue
6
Copyright Statement
© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000419340300016&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Engineering, Biomedical
Engineering, Electrical & Electronic
Engineering
CMOS integrated sensors
ion-sensitive field-effect transistor (ISFET)
pH measurement
sensor arrays
thermoelectric generators (TEGs)
FIELD-EFFECT TRANSISTORS
CMOS ISFET
PERSPIRATION
SYSTEM
Publication Status
Published
Coverage Spatial
San Francisco, CA
Date Publish Online
2017-08-24