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

Abstract

Inexpensive and accurate tools for monitoring conditions in enclosed environments (through garments, bandages, tissue, etc.) have been a long-standing goal of medicine. Passive resonant sensors are a promising solution for such wearable health sensors as well as off-body diagnostics. They are simple circuits with inherent inductance and capacitance (LC tank) that have a measurable resonant frequency. Changes in local parameters, e.g., permittivity or geometry, effect inductance and capacitance which cause a resonant frequency shift response. This signal transduction has been applied to several biomedical applications such as intracranial pressure, hemodynamics, epidermal hydration, etc. Despite these many promising applications presented in the literature, resonant sensors still do not see widespread adoption in biomedical applications, especially as wearable or embedded sensing devices. This perspective highlights some of the current challenges facing LC resonant sensors in biomedical applications, such as positional sensitivity, and potential strategies that have been developed to overcome them. An outlook on adoption in medicine and health monitoring is presented, and a perspective is given on next steps for research in this field.

Single-use, Metabolite Absorbing, Resonant Transducer (SMART) culture vessels for label-free, continuous cell culture progression monitoring

“…Variation in permittivity proximal to the sensor in response to the target analyte is a common sensing modality, as this has a large effect on resonant frequency. [51]…”

“…Variation in permittivity proximal to the sensor in response to the target analyte is a common sensing modality, as this has a large effect on resonant frequency. [51] Two modes of signal transduction are possible when applying resonant sensors to cell culture sensing (Figure 1a). First, cell membranes are composed of a low conductivity phospholipid bilayer that separates the intercellular contents from the surrounding medium, functioning as a capacitor at low frequencies (< 100 kHz).…”

Deep Learning-Enhanced Inverse Modeling of Terahertz Metasurface Based on a Convolutional Neural Network Technique

“…In the process of biomolecular detection and analysis with the SRR, the existence of the substance to be detected will cause the electrical characteristics of the SRR surface to change and then cause the change in the resonant curve. By leveraging the alterations in resonant features exhibited by biological resonant sensors, including shifts in frequency and variations in peak depth, in conjunction with pertinent analytical techniques, it becomes feasible to ascertain various biological properties of the target, spanning from its structural attributes to its compositional makeup [20,21].…”

Flexible Passive Sensor Patch with Contactless Readout for Measurement of Human Body Temperature

“…To achieve this purpose, the exploitation of flexible wearable sensors is progressively emerging as an effective approach for monitoring human body temperature [ 4 , 5 , 6 , 7 ]. Near-Field Communication (NFC)-based temperature sensors have been successfully employed in biomedical applications to develop battery-less skin patches [ 8 ]. These sensors employ on-board active electronic integrated circuits, typically a microcontroller with one or more connected sensors, that have to be energized by a reader to transmit the information retrieved through a digital communication protocol.…”