{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,31]],"date-time":"2026-01-31T01:07:39Z","timestamp":1769821659873,"version":"3.49.0"},"reference-count":27,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2020,11,20]],"date-time":"2020-11-20T00:00:00Z","timestamp":1605830400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the National Instrumentation Program of China","award":["2013YQ040911"],"award-info":[{"award-number":["2013YQ040911"]}]},{"name":"the Key Projects of the National Natural Science Foundation of China","award":["51735011"],"award-info":[{"award-number":["51735011"]}]},{"DOI":"10.13039\/501100001809","name":"the National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51775446"],"award-info":[{"award-number":["51775446"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Hot film sensors detect the flow shear stress based on the forced convection heat transfer to the fluid. Current hot film sensors have been significantly hindered by the relatively low sensitivity due to the massive heat conduction to the substrate. This paper describes the design, fabrication, simulation, and testing of a novel flow sensor with dual-layer hot film structures. More specifically, the heat conduction was insulated from the sensing heater to the substrate by controlling both sensing and guarding heaters working at the same temperature, resulting in a higher sensitivity. The experiment and simulation results showed that the sensitivity of the dual-layer hot film sensor was significantly improved in comparison to the single-layer sensor. Additionally, the dual-layer sensor was designed and fabricated in an integrated, flexible, and miniaturized manner. Its small size makes it an excellent candidate for flow detection.<\/jats:p>","DOI":"10.3390\/s20226657","type":"journal-article","created":{"date-parts":[[2020,11,20]],"date-time":"2020-11-20T09:46:18Z","timestamp":1605865578000},"page":"6657","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Highly Sensitive Flow Sensor Based on Flexible Dual-Layer Heating Structures"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0956-0007","authenticated-orcid":false,"given":"Yu-Chao","family":"Yan","sequence":"first","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Cheng-Yu","family":"Jiang","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Run-Bo","family":"Chen","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Bing-He","family":"Ma","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Jin-Jun","family":"Deng","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Shao-Jun","family":"Zheng","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]},{"given":"Jian","family":"Luo","sequence":"additional","affiliation":[{"name":"Key Lab of Micro\/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi\u2019an 710072, China"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"382","DOI":"10.1038\/s41587-019-0079-1","article-title":"Toward a new generation of smart skins","volume":"37","author":"Someya","year":"2019","journal-title":"Nat. Biotechnol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1800628","DOI":"10.1002\/admt.201800628","article-title":"Multifunctional Skin-Inspired Flexible Sensor Systems for Wearable Electronics","volume":"4","author":"Xu","year":"2019","journal-title":"Adv. Mater. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"16043","DOI":"10.1038\/micronano.2016.43","article-title":"Emerging flexible and wearable physical sensing platforms for healthcare and biomedical applications","volume":"2","author":"Kenry","year":"2016","journal-title":"Microsyst. Nanoeng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3132","DOI":"10.1038\/ncomms4132","article-title":"A wearable and highly sensitive pressure sensor with ultrathin gold nanowires","volume":"5","author":"Shu","year":"2014","journal-title":"Nat. Commun."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"9966","DOI":"10.1073\/pnas.0401918101","article-title":"A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications","volume":"101","author":"Someya","year":"2004","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1652","DOI":"10.1097\/PRS.0000000000001289","article-title":"Providing a Sense of Touch to Prosthetic Hands","volume":"135","author":"Nghiem","year":"2015","journal-title":"Plast. Reconstr. Surg."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"937","DOI":"10.1038\/nmat4671","article-title":"Pursuing prosthetic electronic skin","volume":"15","author":"Chortos","year":"2016","journal-title":"Nat. Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1501","DOI":"10.1126\/science.1126216","article-title":"High-Resolution Thin-Film Device to Sense Texture by Touch","volume":"312","author":"Maheshwari","year":"2006","journal-title":"Science"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1859","DOI":"10.1038\/ncomms2832","article-title":"Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring","volume":"4","author":"Schwartz","year":"2013","journal-title":"Nat. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"12949","DOI":"10.1038\/s41598-017-13281-8","article-title":"Highly sensitive, self-powered and wearable electronic skin based on pressure-sensitive nanofiber woven fabric sensor","volume":"7","author":"Yuman","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"702","DOI":"10.2340\/16501977-1001","article-title":"Sensory feedback from a prosthetic hand based on air-mediated pressure from the hand to the forearm skin","volume":"44","author":"Christian","year":"2012","journal-title":"J. Rehabil. Med."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"850","DOI":"10.1002\/adma.201204082","article-title":"Flexible Wireless Temperature Sensors Based on Ni Microparticle-Filled Binary Polymer Composites","volume":"25","author":"Jin","year":"2013","journal-title":"Adv. Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"11505","DOI":"10.1038\/srep11505","article-title":"Breathable and Stretchable Temperature Sensors Inspired by Skin","volume":"5","author":"Ying","year":"2015","journal-title":"Sci. Rep."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3597","DOI":"10.3390\/s100403597","article-title":"Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite","volume":"10","author":"Chienliu","year":"2010","journal-title":"Sensors"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"43383","DOI":"10.1021\/acsami.9b16336","article-title":"Multifunctional and High-Sensitive Sensor Capable of Detecting Humidity, Temperature, and Flow Stimuli Using an Integrated Microheater","volume":"11","author":"Jin","year":"2019","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1802128","DOI":"10.1002\/advs.201802128","article-title":"A Multiparameter Pressure\u2013Temperature\u2013Humidity Sensor Based on Mixed Ionic\u2013Electronic Cellulose Aerogels","volume":"6","author":"Shaobo","year":"2019","journal-title":"Adv. Sci."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Liu, S.Q., and Zhu, R. (2017). Micromachined Fluid Inertial Sensors. Sensors, 17.","DOI":"10.3390\/s17020367"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1606151","DOI":"10.1002\/adma.201606151","article-title":"Electronic skin with multifunction sensors based on thermosensation","volume":"29","author":"Zhao","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"194","DOI":"10.1016\/S0924-4247(99)00277-0","article-title":"A flexible micromachine-based shear-stress sensor array and its application to separation-point detection","volume":"79","author":"Jiang","year":"2000","journal-title":"Sens. Actuators A"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1115\/1.2817778","article-title":"MEMS and its applications for flow control","volume":"118","author":"Ho","year":"1996","journal-title":"J. Fluids Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.flowmeasinst.2010.03.004","article-title":"Evaluation of hot-film, dual optical and Pitot tube probes for liquid\u2013liquid two-phase flow measurements","volume":"21","author":"Hamad","year":"2010","journal-title":"Flow. Meas. Instrum."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"023512","DOI":"10.1063\/1.4958842","article-title":"A MEMS thermal shear stress sensor produced by a combination of substrate-free structures with anodic bonding technology","volume":"109","author":"Ou","year":"2016","journal-title":"Appl. Phys. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1016\/j.ijheatmasstransfer.2013.11.069","article-title":"Analyzing guard-heating to enable accurate hot-film wall shear stress measurements for turbulent flows","volume":"70","author":"Etrati","year":"2014","journal-title":"Int. J. Heat Mass Transf."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/j.ijheatfluidflow.2013.12.004","article-title":"Frequency response analysis of guard-heated hot-film wall shear stress sensors for turbulent flows","volume":"46","author":"Etrati","year":"2014","journal-title":"Int. J. Heat Fluid Flow"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.taml.2018.02.010","article-title":"An improved wall shear stress measurement technique using sandwiched hot-film sensors","volume":"8","author":"Liu","year":"2018","journal-title":"Theor. Appl. Mech. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105303","DOI":"10.1088\/1361-6501\/aadb1b","article-title":"Toward calibration-free wall shear stress measurement using a dual hot-film sensor and Kelvin bridges","volume":"29","author":"Liu","year":"2018","journal-title":"Meas. Sci. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.sna.2017.08.042","article-title":"Sensing elements space design of hot-film sensor array considering thermal crosstalk","volume":"265","author":"Sun","year":"2017","journal-title":"Sens. Actuator A"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6657\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:35:01Z","timestamp":1760178901000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6657"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,20]]},"references-count":27,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["s20226657"],"URL":"https:\/\/doi.org\/10.3390\/s20226657","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,11,20]]}}}