Sensitivity Enhanced Vital Sign Detection Based on Antenna Reflection Coefficient Variation

An, Yong-Jun; Yun, Gi-Ho; Yook, Jong-Gwan

doi:10.1109/tbcas.2014.2380435

Cited by 25 publications

(8 citation statements)

References 27 publications

(31 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, their sizes can be reduced due to their high operating frequencies, and they can easily be linked with commercial mobile communication systems. Because of these advantages, microwave resonators have been applied in a variety of sensing applications, such as glucose measurement 35 , 36 , biomolecular sensing 37 – 39 , gas sensing 40 , 41 , wrist pulse detection 42 – 44 , vital sign monitoring 45 – 47 , and breast tumour detection 48 , 49 . Additionally, relative humidity detection using microwave components has also been studied 50 , 51 .…”

Section: Introductionmentioning

confidence: 99%

Real-time Humidity Sensor Based on Microwave Resonator Coupled with PEDOT:PSS Conducting Polymer Film

Park

Kang

Kim

et al. 2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

A real-time humidity sensor based on a microwave resonator coupled with a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conducting polymer (CP) film is proposed in this paper. The resonator is patterned on a printed circuit board and is excited by electromagnetic field coupling. To enhance the sensitivity of the sensor, the CP film is located in the area with the strongest electric field in the resonator. To investigate the performance, the proposed sensor is placed alongside a reference sensor in a humidity chamber, and humidity is injected at room temperature. The experimental results indicate that the electrical properties of the resonator with the CP film, such as the transmission coefficient (S 21) and resonance frequency, change with the relative humidity (RH). Specifically, as the RH changes from 5% to 80%, S 21 and the resonance frequency change simultaneously. Moreover, the proposed sensor exhibits great repeatability in the middle of the sensing range, which is from 40% to 60% RH. Consequently, our resonator coupled with the CP film can be used as a real-time humidity-sensing device in the microwave range, where various radio-frequency devices are in use.

show abstract

Section: Introductionmentioning

confidence: 99%

Real-time Humidity Sensor Based on Microwave Resonator Coupled with PEDOT:PSS Conducting Polymer Film

Park

Kang

Kim

et al. 2018

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…To characterise the two-port resonator or the resonator array system, the transmission coefficient is analysed mathematically. Taking the approach similar to that in [23], the transmission coefficient of the resonators can be expressed as…”

Section: System Configurationmentioning

confidence: 99%

“…where k is the characteristic coefficient of the power detector and V ini is the initial output voltage of the detector. Similar to a prior study [23], the output of the detector is analysed to enhance the sensitivity of the sensor. The slope of the power detector within the proposed system can be expressed as…”

Section: System Configurationmentioning

confidence: 99%

See 1 more Smart Citation

RF interferometric wearable wrist pulse detection system

Kim¹,

Yun

et al. 2018

IET Microwaves, Antennas & Propagation

View full text Add to dashboard Cite

This study presents a novel wrist pulse detection system based on the variation of transmission coefficient (S21) of coupled resonators. Radiated signal from one resonator is modulated by the wrist pulse and transmitted to the other resonator. To improve sensitivity of the system, a radio‐frequency (RF) interferometer concept is employed and its validity is mathematically analysed. Full‐wave electromagnetic simulation is conducted with the wrist phantom model to predict the transmission coefficient between resonators. The peak level of the S21 is around −10 dB and the resonance frequency shifts to higher frequency as the distance between the resonator and wrist increases. A prototype of the system is fabricated and tested to show sensitivity enhancement around the 2.4 GHz industry‐science‐medical (ISM) band. Experimental results reveal that the wrist pulse signal measured by the RF interferometer system is in exact coincidence with the reference finger sensor. Also, the sensitivity is enhanced about 23 dB with the RF interferometer system based on the measurement results.

show abstract

“…The utilities of nearfield RF resonators have been studied for several decades in the fields of wearable technologies with different transceiver architectures for detecting cardiopulmonary motion, precordial displacements for respiration rate and heartbeat, radial pulse, intraocular pressure as well as intracranial pressure (ICP) [ 1 , 2 , 5 , 6 , 7 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. However, most applications require rigid antennas as a sensing element or bulky benchtop readout equipment for signal transduction, which lacks epidermal conformance and a wearable form factor.…”

Section: Introductionmentioning

confidence: 99%

A Flexible Near-Field Biosensor for Multisite Arterial Blood Flow Detection

Mohammed

Cluff

Sutton

et al. 2022

Sensors

View full text Add to dashboard Cite

Modern wearable devices show promising results in terms of detecting vital bodily signs from the wrist. However, there remains a considerable need for a device that can conform to the human body’s variable geometry to accurately detect those vital signs and to understand health better. Flexible radio frequency (RF) resonators are well poised to address this need by providing conformable bio-interfaces suitable for different anatomical locations. In this work, we develop a compact wearable RF biosensor that detects multisite hemodynamic events due to pulsatile blood flow through noninvasive tissue–electromagnetic (EM) field interaction. The sensor consists of a skin patch spiral resonator and a wearable transceiver. During resonance, the resonator establishes a strong capacitive coupling with layered dielectric tissues due to impedance matching. Therefore, any variation in the dielectric properties within the near-field of the coupled system will result in field perturbation. This perturbation also results in RF carrier modulation, transduced via a demodulator in the transceiver unit. The main elements of the transceiver consist of a direct digital synthesizer for RF carrier generation and a demodulator unit comprised of a resistive bridge coupled with an envelope detector, a filter, and an amplifier. In this work, we build and study the sensor at the radial artery, thorax, carotid artery, and supraorbital locations of a healthy human subject, which hold clinical significance in evaluating cardiovascular health. The carrier frequency is tuned at the resonance of the spiral resonator, which is 34.5 ± 1.5 MHz. The resulting transient waveforms from the demodulator indicate the presence of hemodynamic events, i.e., systolic upstroke, systolic peak, dicrotic notch, and diastolic downstroke. The preliminary results also confirm the sensor’s ability to detect multisite blood flow events noninvasively on a single wearable platform.

show abstract

Sensitivity Enhanced Vital Sign Detection Based on Antenna Reflection Coefficient Variation

Cited by 25 publications

References 27 publications

Real-time Humidity Sensor Based on Microwave Resonator Coupled with PEDOT:PSS Conducting Polymer Film

Real-time Humidity Sensor Based on Microwave Resonator Coupled with PEDOT:PSS Conducting Polymer Film

RF interferometric wearable wrist pulse detection system

A Flexible Near-Field Biosensor for Multisite Arterial Blood Flow Detection

Contact Info

Product

Resources

About