Skip to main content

Research Repository

Advanced Search

Passive impedance sensing using a SAW resonator-coupled biosensor for zero-power wearable applications

Yue, Xicai; Kiely, Janice; Luxton, Richard; Chen, Boyang; McLeod, Chris N.; Drakakis, Emmanuel M.


Profile Image

Alex Yue
Senior Lecturer in Bioinstrumentation and Sensor Interfacing

Janice Kiely
Professor in Bio-electronics/Res In CoDi

Richard Luxton
Research Centre Director-IBST/Professor

Boyang Chen

Chris N. McLeod

Emmanuel M. Drakakis


A bio-sensing scheme, which acquires impedance information of a capacitive biosensor by using the reflected RF signal from a surface acoustic wave (SAW) resonator connected to the biosensor, is proposed. This technique requires no power to be supplied to the biosensor node and hence is highly applicable to wearable applications. Theoretical analysis has demonstrated that the sensitivity of the SAW resonator-coupled biosensor is higher than that of traditional impedance loaded SAW sensors and therefore it is more suitable for measuring the very small impedance changes in biosensors. The passive detection of the change in the impedance of a capacitive biosensor, as a result of biological binding events associated with the capture of a target analyte, has been demonstrated by preliminary experimentation. Dry tests of the SAW coupled capacitive biosensor using a cable connected network analyzer showed the aF level capacitance measurement resolution, which was only achieved in transistor level circuits previously, could be attained. When liquid samples with concentrations of C-Reactive Protein (CRP) in the range of 0.1 to 2 μg/ml were applied to the biosensor, a corresponding change in the resonant frequency of the SAW resonator-coupled biosensor (in the order of sub-hundred kHz) was observed. This has demonstrated the potential for applying this technique in applications where a zero-power requirement at the biosensor node could be a distinct advantage, when the cable link between the network analyzer and the biosensor node is replaced by the RF transmission.


Yue, X., Kiely, J., Luxton, R., Chen, B., McLeod, C. N., & Drakakis, E. M. (2022). Passive impedance sensing using a SAW resonator-coupled biosensor for zero-power wearable applications. IEEE Sensors Journal, 22(3), 2347-2357.

Journal Article Type Article
Acceptance Date Dec 5, 2021
Online Publication Date Dec 20, 2021
Publication Date Feb 1, 2022
Deposit Date Jan 13, 2022
Publicly Available Date Jan 13, 2022
Journal IEEE Sensors Journal
Print ISSN 1530-437X
Electronic ISSN 1558-1748
Publisher Institute of Electrical and Electronics Engineers
Peer Reviewed Peer Reviewed
Volume 22
Issue 3
Pages 2347-2357
Keywords Electrical and Electronic Engineering; Instrumentation
Public URL


You might also like

Downloadable Citations