Feasibility of dual-heat-flux thermometry in estimating human body temperature
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Journal Title
Journal ISSN
Volume Title
Sähkötekniikan korkeakoulu |
Master's thesis
Authors
Date
2019-03-11
Department
Major/Subject
Control, Robotics and Autonomous Systems
Mcode
ELEC3025
Degree programme
AEE - Master’s Programme in Automation and Electrical Engineering (TS2013)
Language
en
Pages
62+1
Series
Abstract
Core body temperature can be defined as the temperature of the inner organs of the body. The definition is vague in a sense that temperature of the organs depends on their activity time. Temperature of the blood in pulmonary artery can be considered as the best representation of body’s internal average temperature. Bladder catheter, rectal and esophageal probes have been used as invasivetechniques for core temperature estimation and are uncomfortable in long-term continuous monitoring. Need to continuously monitor mobile patients comfortably, paved way for subjects like infrared and heat-flux thermometry. Zero-heat-flux thermometry demands a servo-controlled heater element to achieve isothermal condition where the core temperature is brought out to skin surface and is then measured. Need of establishing this condition renders the technique energy hungry therefore; unsuitable for battery operated systems. Dual-heat-flux thermometry, a derivative of non-zero-heat flux thermometry, is a passive core temperature measuring technique which makes use of the temperatures established across two paths of unequal and known thermal resistances. The technique, being passive in nature, is more prone to environmental artifacts. This thesis aims at studying the feasibility of dual-heat-flux thermometry in hospital environment by using 3M SpotOn as reference. The interferences studied include variation in ambient temperature, change in air convection, effect of radiation and introduction of clothing. Modifications in sensor structure covers changing thickness of probe, altering thermal conductivity of insulation material and introducing shielding on sensor structure. Results show that dual-heat-flux thermometry can provide accurate core temperature estimation. However, for this technique to be of practical use, controlling the effect of non-idealities such as unequal ambient resistance, lateral heat flow, heat dissipation from sensor probe and unreliable thermal contact is important.Description
Supervisor
Laakso, IlkkaThesis advisor
Virtanen, JuhaKeywords
core body temperature, non-invasive thermometry, dual-heat-flux, patient monitoring