{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/109370"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/109370","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Transient intra- and extra-cellular thermometry as probes of thermogenesis","abstract":"Temperature is a fundamental thermodynamic property affecting every biochemical reaction in cellular milieu. Thermometry in tissues has proven useful in understanding thermoregulatory neuronal circuits and cancer metabolism. In contrast, intracellular temperature changes are relatively less explored. Theoretical temperature changes in intracellular organelles are widely debated, due to lack of understanding of intracellular thermal resistances. There is thus a need for thermometry techniques that can probe within a cell. Such intracellular thermometry can inform theory, and more importantly, provide insight into the role of temperature as a physiological parameter in intracellular studies. In this work, we describe an intracellular thermometry technique developed using silicon-based microelectromechanical techniques. We fabricated a 5 μm wide micro-thermocouple probe that has a calibration accuracy of 1% and a time constant of 32 μs. Through this probe, we measured transient temperature changes during stimulated mitochondrial proton uncoupling in neurons of Aplysia californica. We find that a transient proton motive force dissipation is more dominant than steady-state substrate oxidation in stimulated thermogenesis. Our measurements demonstrate the utility of transient intracellular thermometry in better understanding the thermochemistry of stimulated mitochondrial metabolism. Using insights from intracellular thermometry, we theoretically examine the validity of thermal conductivity approximation and find that the thermal interfacial resistances might dominate in the sub-cellular region. We develop a generalized thermal resistance network model to analyze cellular-level temperature changes. We find that intracellular temperature changes could be useful to probe stimulated transient biochemical reactions that can produce higher intracellular temperatures, which may not occur endogenously. On the other hand, to probe endogenously thermogenic reactions, we find extracellular thermometry to be better suited, especially at length-scales > 1 cm, such as tissues or organs. To this end, we develop a wireless temperature measurement technique using magnetostriction based sensors that can potentially measure temperatures at tissues length-scales remotely. We identify material properties that influence temperature sensitivity and demonstrate a 5-fold improvement through optimal selection. We further develop techniques that reduce instrument complexity and discuss ways to miniaturize wireless sensors. Overall, this work advances intra- and extra-cellular thermometry techniques that potentially provide unprecedented insight into thermogenesis in cells.","abstract_html":"Temperature is a fundamental thermodynamic property affecting every biochemical reaction in cellular milieu. Thermometry in tissues has proven useful in understanding thermoregulatory neuronal circuits and cancer metabolism. In contrast, intracellular temperature changes are relatively less explored. Theoretical temperature changes in intracellular organelles are widely debated, due to lack of understanding of intracellular thermal resistances. There is thus a need for thermometry techniques that can probe within a cell. Such intracellular thermometry can inform theory, and more importantly, provide insight into the role of temperature as a physiological parameter in intracellular studies. In this work, we describe an intracellular thermometry technique developed using silicon-based microelectromechanical techniques. We fabricated a 5 μm wide micro-thermocouple probe that has a calibration accuracy of 1% and a time constant of 32 μs. Through this probe, we measured transient temperature changes during stimulated mitochondrial proton uncoupling in neurons of Aplysia californica. We find that a transient proton motive force dissipation is more dominant than steady-state substrate oxidation in stimulated thermogenesis. Our measurements demonstrate the utility of transient intracellular thermometry in better understanding the thermochemistry of stimulated mitochondrial metabolism. Using insights from intracellular thermometry, we theoretically examine the validity of thermal conductivity approximation and find that the thermal interfacial resistances might dominate in the sub-cellular region. We develop a generalized thermal resistance network model to analyze cellular-level temperature changes. We find that intracellular temperature changes could be useful to probe stimulated transient biochemical reactions that can produce higher intracellular temperatures, which may not occur endogenously. On the other hand, to probe endogenously thermogenic reactions, we find extracellular thermometry to be better suited, especially at length-scales > 1 cm, such as tissues or organs. To this end, we develop a wireless temperature measurement technique using magnetostriction based sensors that can potentially measure temperatures at tissues length-scales remotely. We identify material properties that influence temperature sensitivity and demonstrate a 5-fold improvement through optimal selection. We further develop techniques that reduce instrument complexity and discuss ways to miniaturize wireless sensors. Overall, this work advances intra- and extra-cellular thermometry techniques that potentially provide unprecedented insight into thermogenesis in cells.","abstract_has_math":false,"creators":["Chinnappamudaliar Rajagopal, Manjunath"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Sinha, Sanjiv","Gillette, Rhanor","Llano, Daniel","Ferreira, Placid"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-03-05T21:37:59Z","date_published":"2021-03-05T21:37:59Z","updated_at":"2026-07-22T22:24:50Z","subjects":["intracellular thermometry","thermogenesis","mitochondrial heat","metabolic pathways","cellular heat diffusion","biosensors","microfabrication","wireless thermometry"],"languages":["en"],"rights":["Copyright 2020 Manjunath Chinnappamudaliar Rajagopal"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/109370","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Sinha, Sanjiv","Gillette, Rhanor","Llano, Daniel","Ferreira, Placid"]},{"key":"dc:creator","label":"Author","values":["Chinnappamudaliar Rajagopal, Manjunath"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2021-03-05T21:37:59Z","2020-11-23","2020-12"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["intracellular thermometry","thermogenesis","mitochondrial heat","metabolic pathways","cellular heat diffusion","biosensors","microfabrication","wireless thermometry"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Manjunath Chinnappamudaliar Rajagopal"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/109370"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Temperature is a fundamental thermodynamic property affecting every biochemical reaction in cellular milieu. Thermometry in tissues has proven useful in understanding thermoregulatory neuronal circuits and cancer metabolism. In contrast, intracellular temperature changes are relatively less explored. Theoretical temperature changes in intracellular organelles are widely debated, due to lack of understanding of intracellular thermal resistances. There is thus a need for thermometry techniques that can probe within a cell. Such intracellular thermometry can inform theory, and more importantly, provide insight into the role of temperature as a physiological parameter in intracellular studies. In this work, we describe an intracellular thermometry technique developed using silicon-based microelectromechanical techniques. We fabricated a 5 μm wide micro-thermocouple probe that has a calibration accuracy of 1% and a time constant of 32 μs. Through this probe, we measured transient temperature changes during stimulated mitochondrial proton uncoupling in neurons of Aplysia californica. We find that a transient proton motive force dissipation is more dominant than steady-state substrate oxidation in stimulated thermogenesis. Our measurements demonstrate the utility of transient intracellular thermometry in better understanding the thermochemistry of stimulated mitochondrial metabolism. Using insights from intracellular thermometry, we theoretically examine the validity of thermal conductivity approximation and find that the thermal interfacial resistances might dominate in the sub-cellular region. We develop a generalized thermal resistance network model to analyze cellular-level temperature changes. We find that intracellular temperature changes could be useful to probe stimulated transient biochemical reactions that can produce higher intracellular temperatures, which may not occur endogenously. On the other hand, to probe endogenously thermogenic reactions, we find extracellular thermometry to be better suited, especially at length-scales > 1 cm, such as tissues or organs. To this end, we develop a wireless temperature measurement technique using magnetostriction based sensors that can potentially measure temperatures at tissues length-scales remotely. We identify material properties that influence temperature sensitivity and demonstrate a 5-fold improvement through optimal selection. We further develop techniques that reduce instrument complexity and discuss ways to miniaturize wireless sensors. Overall, this work advances intra- and extra-cellular thermometry techniques that potentially provide unprecedented insight into thermogenesis in cells.","Submission original under an indefinite embargo labeled 'Open Access'. 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Thermometry in tissues has proven useful in understanding thermoregulatory neuronal circuits and cancer metabolism. In contrast, intracellular temperature changes are relatively less explored. Theoretical temperature changes in intracellular organelles are widely debated, due to lack of understanding of intracellular thermal resistances. There is thus a need for thermometry techniques that can probe within a cell. Such intracellular thermometry can inform theory, and more importantly, provide insight into the role of temperature as a physiological parameter in intracellular studies. In this work, we describe an intracellular thermometry technique developed using silicon-based microelectromechanical techniques. We fabricated a 5 μm wide micro-thermocouple probe that has a calibration accuracy of 1% and a time constant of 32 μs. Through this probe, we measured transient temperature changes during stimulated mitochondrial proton uncoupling in neurons of Aplysia californica. We find that a transient proton motive force dissipation is more dominant than steady-state substrate oxidation in stimulated thermogenesis. Our measurements demonstrate the utility of transient intracellular thermometry in better understanding the thermochemistry of stimulated mitochondrial metabolism. Using insights from intracellular thermometry, we theoretically examine the validity of thermal conductivity approximation and find that the thermal interfacial resistances might dominate in the sub-cellular region. We develop a generalized thermal resistance network model to analyze cellular-level temperature changes. We find that intracellular temperature changes could be useful to probe stimulated transient biochemical reactions that can produce higher intracellular temperatures, which may not occur endogenously. On the other hand, to probe endogenously thermogenic reactions, we find extracellular thermometry to be better suited, especially at length-scales > 1 cm, such as tissues or organs. To this end, we develop a wireless temperature measurement technique using magnetostriction based sensors that can potentially measure temperatures at tissues length-scales remotely. We identify material properties that influence temperature sensitivity and demonstrate a 5-fold improvement through optimal selection. We further develop techniques that reduce instrument complexity and discuss ways to miniaturize wireless sensors. Overall, this work advances intra- and extra-cellular thermometry techniques that potentially provide unprecedented insight into thermogenesis in cells.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2021-03-04 without embargo terms","The student, Manjunath Chinnappamudaliar Rajagopal, accepted the attached license on 2020-11-19 at 11:10.","The student, Manjunath Chinnappamudaliar Rajagopal, submitted this Dissertation for approval on 2020-11-19 at 11:37.","This Dissertation was approved for publication on 2020-11-23 at 14:31.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15912 on 2021-03-04 at 15:34:45","Made available in DSpace on 2021-03-05T21:37:59Z (GMT). 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