Materials and Orthopedic Applications for Bioresorbable Inductively Coupled Resonance Sensors.

Aleksi Palmroth,Minna Kellomäki,Petri Vuoristo,Timo Salpavaara,Sanna Karjalainen,Susanna Miettinen,Tommi Kääriäinen,Jukka Lekkala,Jonathan Massera

doi:10.1021/acsami.0c07278

Aleksi Palmroth, Minna Kellomäki + Show 7 more

Open Access

https://doi.org/10.1021/acsami.0c07278

Copy DOI

Abstract

Bioresorbable passive resonance sensors based on inductor–capacitor (LC) circuits provide an auspicious sensing technology for temporary battery-free implant applications due to their simplicity, wireless readout, and the ability to be eventually metabolized by the body. In this study, the fabrication and performance of various LC circuit-based sensors are investigated to provide a comprehensive view on different material options and fabrication methods. The study is divided into sections that address different sensor constituents, including bioresorbable polymer and bioactive glass substrates, dissolvable metallic conductors, and atomic layer deposited (ALD) water barrier films on polymeric substrates. The manufactured devices included a polymer-based pressure sensor that remained pressure responsive for 10 days in aqueous conditions, the first wirelessly readable bioactive glass-based resonance sensor for monitoring the complex permittivity of its surroundings, and a solenoidal coil-based compression sensor built onto a polymeric bone fixation screw. The findings together with the envisioned orthopedic applications provide a reference point for future studies related to bioresorbable passive resonance sensors.

Highlights

Implantable sensors have been used for research purposes as part of orthopedic fixation devices for decades, but their clinical usage has remained scarce
Sensors made from bioresorbable materials are designed to operate for a defined time under physiological conditions, after which they degrade into nontoxic substances that can be eliminated from the body.[5,6]
This study summarizes the prospects and caveats in the assembly, testing, and performance of wireless inductor− capacitor (LC) resonance sensors fabricated by using bioresorbable materials, as well as outlines several potential orthopedic applications for such devices

Summary

Introduction

Implantable sensors have been used for research purposes as part of orthopedic fixation devices for decades, but their clinical usage has remained scarce. The early smart implant systems utilized percutaneous wires for power and data transfer, but the wires are known to increase infection risks and may constrain the device usage to hospital surroundings.[1−3] One approach for wireless sensor systems involves inductively coupled passive resonance sensors, which essentially consist of a parallel circuit of an inductor (L) coil and a capacitor (C). Such sensors operate without batteries, which reduces their size and complexity, making them easier to integrate into orthopedic implants.[4] As a recent approach, sensors made from bioresorbable materials are designed to operate for a defined time under physiological conditions, after which they degrade into nontoxic substances that can be eliminated from the body.[5,6]. A review by Huang et al discusses the operational principle and state-of-the-art of these sensors in more detail.[7]

Objectives

Results

Conclusion