MAS: Standalone Microwave Resonator to Assess Muscle Quality

Abstract

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

A Novel Microwave Resonant Sensor for Measuring Cancer Cell Line Aggressiveness

“…Microwave sensors offer the possibility of measuring living tissue's dielectric properties through noninvasive scattering parameters [9]. Changes in these factors, which are strictly related to the resonant frequency of the probe, could be crucial for monitoring or diagnosing possible pathological states [10,11]. For instance, different sensing devices have been used for monitoring vital signs (e.g., heart rate, blood pressure, and blood glucose) [12,13], as well as for the detection of specific biomolecules [14], or even diseases such as cancer and Parkinson disease [15][16][17].…”

Open-Ended Transmission Coaxial Probes for Sarcopenia Assessment

“…For the latter, while the standard circuit analysis implies an open circuit, that open circuit impedance is applied very uniformly across the entire bandwidth. In this way, the fringing transmitted signals can provide broad spectrum characterization of the interrogated target without the unpredictable lobes and nulls that one might observe when operating outside the designated operating bandwidth of a narrower band conventional antenna [47]. Complementary to this is the fact that the signals only need to propagate a few centimeters from one aperture to the other, largely through the target or tissue comprising the space between the two.…”

Contact-Free, Passive, Electromagnetic Resonant Sensors for Enclosed Biomedical Applications: A Perspective on Opportunities and Challenges

“…Copyright 2020 IEEE). (b) On-body sensors: (iv) muscle tissue analysis bandstop LC resonant sensor (Reprinted with permission from ref . Copyright 2021 MDPI), (v) LC resonant sensor for monitoring hemodynamics in arm (Reprinted with permission from ref .…”

“…Resonators utilize radio and microwave frequencies which generate long wavelengths in the electromagnetic spectrum (Figure ), which translates to larger electric fields and measurement of bulk properties of a sample. This is ideal for measuring widespread properties such as tissue dielectric, intracranial pressure, and temperature . However, because their sensing region can be up to a few centimeters, it is difficult to render resonant sensors specific to a single analyte.…”