Resonant cavity perturbation: a promising new method for the assessment of total body water in children

Oldroyd, B.; Robinson, M.P.; Lindley, Elizabeth; Rhodes, Laura A.; Hind, Karen

doi:10.1088/0967-3334/36/12/2503

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…As reviewed in [2], several microwave frequency approaches to hydration monitoring have been previously explored. These include whole body measures using a resonant cavity [15,16], measurements of the skin [17], as well as measurements of the skin and underlying fat layer [18]. In [19], attenuation through the wrist was measured and related to hydration via a complex model.…”

Section: Introductionmentioning

confidence: 99%

Microwave Hydration Monitoring: System Assessment Using Fasting Volunteers

Besler

Fear

2021

Sensors

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Hydration is an important aspect of human health, as water is a critical nutrient used in many physiological processes. However, there is currently no clinical gold standard for non-invasively assessing hydration status. Recent work has suggested that permittivity in the microwave frequency range provides a physiologically meaningful metric for hydration monitoring. Using a simple time of flight technique for estimating permittivity, this study investigates microwave-based hydration assessment using a population of volunteers fasting during Ramadan. Volunteers are measured throughout the day while fasting during Ramadan and while not fasting after Ramadan. Comparing the estimated changes in permittivity to changes in weight and the time s fails to establish a clear relationship between permittivity and hydration. Assessing the subtle changes in hydration found in a population of sedentary, healthy adults proves difficult and more work is required to determine approaches suitable for tracking subtle changes in hydration over time with microwave-based hydration assessment techniques.

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Section: Introductionmentioning

confidence: 99%

Microwave Hydration Monitoring: System Assessment Using Fasting Volunteers

Besler

Fear

2021

Sensors

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“…Various researchers have found that the shape factor can be reduced by combining measurements with the test object in two or more orientations, e.g. Kraszewski and Nelson (1990) looking at seeds, and Oldroyd et al (2015) measuring total body water (TBW) in human subjects. In this paper we demonstrate a novel method of removing the shape factor completely, by comparing to an object of the same shape and known dielectric properties, as illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Dielectric replica measurement: a new technique for obtaining the complex permittivity of irregularly shaped objects

Robinson¹,

Fitton²,

Little³

et al. 2019

Meas. Sci. Technol.

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Dielectric measurements provide valuable information about the properties of materials, and could be used to classify and identify the source of objects in fields such as archaeology. Current methods of identification are all partly destructive, so an innovative electromagnetic method developed by the authors, based on resonant cavity perturbation (RCP), provides an attractive, non-destructive alternative. A problem with traditional RCP is that the changes in frequency and Q-factor vary with the object's shape; however, we overcome this by creating a replica of the object, from a material whose dielectric properties are known. Then, by combining three separate perturbations with orthogonal field directions, due firstly to the object and then to its replica, we eliminate the shape dependency, and thus determine the object's dielectric constant and loss factor. After developing the theory of this novel DRM technique, we demonstrate the principle using a set of geometric shapes made in both polytetrafluoroethylene and a 3D printed material. Further measurements then enable secondorder terms to be included in the model, improving its accuracy. Finally, DRM is shown to be capable of distinguishing two irregularly shaped objects of different materials. Potential applications of DRM include determining the provenance of pottery, glasses and flints, and distinguishing ivory from bone. These would be of interest to customs and environmental agencies, as well as museum curators and archaeologists.

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Engineering Approaches to Assessing Hydration Status

Garrett

Rae

Fletcher

et al. 2018

IEEE Rev. Biomed. Eng.

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Dehydration is a common condition characterized by a decrease in total body water. Acute dehydration can cause physical and cognitive impairment, heat stroke and exhaustion, and, if severe and uncorrected, even death. The health effects of chronic mild dehydration are less well studied with urolithiasis (kidney stones) the only condition consistently associated with it. Aside from infants and those with particular medical conditions, athletes, military personnel, manual workers, and older adults are at particular risk of dehydration due to their physical activity, environmental exposure, and/or challenges in maintaining fluid homeostasis. This review describes the different approaches that have been explored for hydration assessment in adults. These include clinical indicators perceived by the patient or detected by a practitioner and routine laboratory analyses of blood and urine. These techniques have variable accuracy and practicality outside of controlled environments, creating a need for simple, portable, and rapid hydration monitoring devices. We review the wide array of devices proposed for hydration assessment based on optical, electromagnetic, chemical, and acoustical properties of tissue and bodily fluids. However, none of these approaches has yet emerged as a reliable indicator in diverse populations across various settings, motivating efforts to develop new methods of hydration assessment.

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Resonant cavity perturbation: a promising new method for the assessment of total body water in children

Cited by 3 publications

References 26 publications

Microwave Hydration Monitoring: System Assessment Using Fasting Volunteers

Microwave Hydration Monitoring: System Assessment Using Fasting Volunteers

Dielectric replica measurement: a new technique for obtaining the complex permittivity of irregularly shaped objects

Engineering Approaches to Assessing Hydration Status

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