An ex vivo study of wireless linkage distance between implantable LC resonance sensor and external readout coil

Muhammad Farooq*, Bilal Amin, Marcin J. Kraśny, Adnan Elahi, Muhammad Riaz ur Rehman, William Wijns, Atif Shahzad

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

The wireless monitoring of key physiological parameters such as heart rate, respiratory rate, temperature, and pressure can aid in preventive healthcare, early diagnosis, and patient-tailored treatment. In wireless implantable sensors, the distance between the sensor and the reader device is prone to be influenced by the operating frequency, as well as by the medium between the sensor and the reader. This manuscript presents an ex vivo investigation of the wireless linkage between an implantable sensor and an external reader for medical applications. The sensor was designed and fabricated using a cost-effective and accessible fabrication process. The sensor is composed of a circular planar inductor (L) and a circular planar capacitor (C) to form an inductor–capacitor (LC) resonance tank circuit. The reader system comprises a readout coil and data acquisition instrumentation. To investigate the effect of biological medium on wireless linkage, the readout distance between the sensor and the readout coil was examined independently for porcine and ovine tissues. In the bench model, to mimic the bio-environment for the investigation, skin, muscle, and fat tissues were used. The relative magnitude of the reflection coefficient (S11) at the readout coil was used as a metric to benchmark wireless linkage. A readable linkage signal was observed on the readout coil when the sensor was held up to 2.5 cm under layers of skin, muscle, and fat tissue. To increase the remote readout distance of the LC sensor, the effect of the repeater coil was also investigated. The experimental results showed that the magnitude of the reflection coefficient signal was increased 3–3.5 times in the presence of the repeater coil, thereby increasing the signal-to-noise ratio of the detected signal. Therefore, the repeater coil between the sensor and the readout coil allows a larger sensing range for a variety of applications in implanted or sealed fields.

Original languageEnglish
Article number8402
Number of pages16
JournalSensors
Volume22
Issue number21
DOIs
Publication statusPublished - 1 Nov 2022

Bibliographical note

Funding Information:
The research leading to this publication was funded by the Science Foundation Ireland Research Professorship Award (grant no. 15/RP/2765) and the Government of Ireland Disruptive Technology Innovation Fund (grant no. DT20180031A). A.S. also acknowledges the funding support from University of Birmingham Dynamic Investment Fund (DIF).

Publisher Copyright:
© 2022 by the authors.

Keywords

  • bio-environment
  • implantable sensor
  • LC sensor
  • physiological parameters
  • repeater coil
  • wireless linkage

ASJC Scopus subject areas

  • Analytical Chemistry
  • Information Systems
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering

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