{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/132624"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/132624","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Toward structural design of ultra-thin and flexible sensors","abstract":"Developing the next generation of flexible and wearable sensors will require concurrent improvements in both the materials and mechanics that such sensors are built upon. In this dissertation, I build upon prior work developing stretchable kirigami graphene sensors and flexible temperature-sensing pectin films to further improve their performance, robustness, sensitivity, and application. My first study presents a kirigami-patterned graphene mesh structure that achieves multiaxial stretchability and multifunctional sensing with minimal motion artifacts. I demonstrate insensitivity to multiaxial strain, including 180° torsion and 100% biaxial strain. As a proof-of-concept, I show a biaxially stretchable kirigami graphene sensor array capable of temperature and glucose concentration sensing with robust signal stability. My second study presents thermal radiation sensors based on ionic-conducting pectin films. I first improve on prior art by increasing the robustness and reliability of temperature-sensitive pectin films, extending their performance lifetimes from several hours to several days. I then demonstrate the resulting robust pectin film sensors in an array configuration for thermal radiation sensing and validate their performance against theoretical models for radiative heat transfer. My final study combines the two previous works by integrating graphene electrodes together with pectin films in a novel geometric configuration. In particular, I show that switching the current direction from across the lateral dimension of the pectin thin films to through their thickness drastically increases the baseline conductivity. I additionally present some equivalent electric circuit models for electric conduction through pectin film sensors and discuss how different configurations and materials play a role in the overall performance. I lastly demonstrate the novel graphene-pectin composite sensors in an array configuration as a fully optically transparent touch-free interface for detecting user input.","abstract_html":"Developing the next generation of flexible and wearable sensors will require concurrent improvements in both the materials and mechanics that such sensors are built upon. In this dissertation, I build upon prior work developing stretchable kirigami graphene sensors and flexible temperature-sensing pectin films to further improve their performance, robustness, sensitivity, and application. My first study presents a kirigami-patterned graphene mesh structure that achieves multiaxial stretchability and multifunctional sensing with minimal motion artifacts. I demonstrate insensitivity to multiaxial strain, including 180° torsion and 100% biaxial strain. As a proof-of-concept, I show a biaxially stretchable kirigami graphene sensor array capable of temperature and glucose concentration sensing with robust signal stability. My second study presents thermal radiation sensors based on ionic-conducting pectin films. I first improve on prior art by increasing the robustness and reliability of temperature-sensitive pectin films, extending their performance lifetimes from several hours to several days. I then demonstrate the resulting robust pectin film sensors in an array configuration for thermal radiation sensing and validate their performance against theoretical models for radiative heat transfer. My final study combines the two previous works by integrating graphene electrodes together with pectin films in a novel geometric configuration. In particular, I show that switching the current direction from across the lateral dimension of the pectin thin films to through their thickness drastically increases the baseline conductivity. I additionally present some equivalent electric circuit models for electric conduction through pectin film sensors and discuss how different configurations and materials play a role in the overall performance. I lastly demonstrate the novel graphene-pectin composite sensors in an array configuration as a fully optically transparent touch-free interface for detecting user input.","abstract_has_math":false,"creators":["Hsieh, Ezekiel Yatung"],"institution":"University of Illinois Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Nam, SungWoo","Hsiao-Wecksler, Elizabeth T","van der Zande, Arend","Diao, Ying"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12","date_published":"2025-12","updated_at":"2026-07-22T22:25:07Z","subjects":["pectin","graphene","kirigami"],"languages":["en"],"rights":["Copyright 2025 Ezekiel Hsieh"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/132624","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Nam, SungWoo","Hsiao-Wecksler, Elizabeth T","van der Zande, Arend","Diao, Ying"]},{"key":"dc:creator","label":"Author","values":["Hsieh, Ezekiel Yatung"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2025-12","2025-09-11"]},{"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 Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["pectin","graphene","kirigami"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2025 Ezekiel Hsieh"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/132624"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Developing the next generation of flexible and wearable sensors will require concurrent improvements in both the materials and mechanics that such sensors are built upon. In this dissertation, I build upon prior work developing stretchable kirigami graphene sensors and flexible temperature-sensing pectin films to further improve their performance, robustness, sensitivity, and application. My first study presents a kirigami-patterned graphene mesh structure that achieves multiaxial stretchability and multifunctional sensing with minimal motion artifacts. I demonstrate insensitivity to multiaxial strain, including 180° torsion and 100% biaxial strain. As a proof-of-concept, I show a biaxially stretchable kirigami graphene sensor array capable of temperature and glucose concentration sensing with robust signal stability. My second study presents thermal radiation sensors based on ionic-conducting pectin films. I first improve on prior art by increasing the robustness and reliability of temperature-sensitive pectin films, extending their performance lifetimes from several hours to several days. I then demonstrate the resulting robust pectin film sensors in an array configuration for thermal radiation sensing and validate their performance against theoretical models for radiative heat transfer. My final study combines the two previous works by integrating graphene electrodes together with pectin films in a novel geometric configuration. In particular, I show that switching the current direction from across the lateral dimension of the pectin thin films to through their thickness drastically increases the baseline conductivity. I additionally present some equivalent electric circuit models for electric conduction through pectin film sensors and discuss how different configurations and materials play a role in the overall performance. I lastly demonstrate the novel graphene-pectin composite sensors in an array configuration as a fully optically transparent touch-free interface for detecting user input.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01","The student, Ezekiel Hsieh, accepted the attached license on 2025-09-10 at 12:45.","The student, Ezekiel Hsieh, submitted this Dissertation for approval on 2025-09-10 at 12:53.","This Dissertation was approved for publication on 2025-09-11 at 16:00.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22798 on 2026-02-19 at 18:45:30"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Toward structural design of ultra-thin and flexible sensors"]}]}],"canonical_facts":{"dc:contributor":["Nam, SungWoo","Hsiao-Wecksler, Elizabeth T","van der Zande, Arend","Diao, Ying"],"dc:creator":["Hsieh, Ezekiel Yatung"],"dc:date":["2025-12","2025-09-11"],"dc:description":["Developing the next generation of flexible and wearable sensors will require concurrent improvements in both the materials and mechanics that such sensors are built upon. In this dissertation, I build upon prior work developing stretchable kirigami graphene sensors and flexible temperature-sensing pectin films to further improve their performance, robustness, sensitivity, and application. My first study presents a kirigami-patterned graphene mesh structure that achieves multiaxial stretchability and multifunctional sensing with minimal motion artifacts. I demonstrate insensitivity to multiaxial strain, including 180° torsion and 100% biaxial strain. As a proof-of-concept, I show a biaxially stretchable kirigami graphene sensor array capable of temperature and glucose concentration sensing with robust signal stability. My second study presents thermal radiation sensors based on ionic-conducting pectin films. I first improve on prior art by increasing the robustness and reliability of temperature-sensitive pectin films, extending their performance lifetimes from several hours to several days. I then demonstrate the resulting robust pectin film sensors in an array configuration for thermal radiation sensing and validate their performance against theoretical models for radiative heat transfer. My final study combines the two previous works by integrating graphene electrodes together with pectin films in a novel geometric configuration. In particular, I show that switching the current direction from across the lateral dimension of the pectin thin films to through their thickness drastically increases the baseline conductivity. I additionally present some equivalent electric circuit models for electric conduction through pectin film sensors and discuss how different configurations and materials play a role in the overall performance. I lastly demonstrate the novel graphene-pectin composite sensors in an array configuration as a fully optically transparent touch-free interface for detecting user input.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-12-01","The student, Ezekiel Hsieh, accepted the attached license on 2025-09-10 at 12:45.","The student, Ezekiel Hsieh, submitted this Dissertation for approval on 2025-09-10 at 12:53.","This Dissertation was approved for publication on 2025-09-11 at 16:00.","DSpace SAF Submission Ingestion Package generated from Vireo submission #22798 on 2026-02-19 at 18:45:30"],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/132624"],"dc:language":["en"],"dc:rights":["Copyright 2025 Ezekiel Hsieh"],"dc:subject":["pectin","graphene","kirigami"],"dc:title":["Toward structural design of ultra-thin and flexible sensors"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:07Z"}