{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T02:24:46Z","timestamp":1773973486891,"version":"3.50.1"},"reference-count":34,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2013,12,23]],"date-time":"2013-12-23T00:00:00Z","timestamp":1387756800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>For devices such as bio-\/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN) and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL\/min and the thinnest SU-8 cantilevers a detection limit below 5 nL\/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.<\/jats:p>","DOI":"10.3390\/s140100229","type":"journal-article","created":{"date-parts":[[2013,12,23]],"date-time":"2013-12-23T12:17:19Z","timestamp":1387801039000},"page":"229-244","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":38,"title":["Integrated Cantilever-Based Flow Sensors with Tunable Sensitivity for In-Line Monitoring of Flow Fluctuations in Microfluidic Systems"],"prefix":"10.3390","volume":"14","author":[{"given":"Nadine","family":"Noeth","sequence":"first","affiliation":[{"name":"Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345E, DK-2800 Kgs. Lyngby, Denmark"}]},{"given":"Stephan","family":"Keller","sequence":"additional","affiliation":[{"name":"Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345E, DK-2800 Kgs. Lyngby, Denmark"}]},{"given":"Anja","family":"Boisen","sequence":"additional","affiliation":[{"name":"Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Building 345E, DK-2800 Kgs. Lyngby, Denmark"}]}],"member":"1968","published-online":{"date-parts":[[2013,12,23]]},"reference":[{"key":"ref_1","first-page":"525","article-title":"Miniaturized total analysis systems for biological analysis","volume":"366","author":"Jakeway","year":"2000","journal-title":"J. Anal. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1146\/annurev.bioeng.4.112601.125916","article-title":"Physics and applications of microfluidics in biology","volume":"4","author":"Beebe","year":"2002","journal-title":"Ann. Rev. Biomed Eng."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3498","DOI":"10.1002\/elps.200406108","article-title":"Recent developments in detection for microfluidic systems","volume":"25","author":"Mogensen","year":"2004","journal-title":"Electrophoresis"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"036101","DOI":"10.1088\/0034-4885\/74\/3\/036101","article-title":"Cantilever-like micromechanical sensors","volume":"74","author":"Boisen","year":"2011","journal-title":"Rep. Prog. Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1088\/0960-1317\/3\/4\/002","article-title":"Microfluidics\u2014A review","volume":"3","author":"Gravesen","year":"1993","journal-title":"J. Micromech. Microeng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1063\/1.1387591","article-title":"Flexible methods for microfluidics","volume":"54","author":"Whitesides","year":"2001","journal-title":"Phys. Today."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/S0955-5986(97)00019-8","article-title":"Micromachined flow sensors\u2014A review","volume":"8","author":"Nguyen","year":"1997","journal-title":"Flow. Meas. Instrum."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"550","DOI":"10.3390\/mi3030550","article-title":"Micromachined thermal flow sensors\u2014A review","volume":"3","author":"Kuo","year":"2012","journal-title":"Micromachines"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/S0924-4247(98)00248-9","article-title":"Thermal flow sensor for liquids and gases based on combinations of two principles","volume":"73","author":"Ashauer","year":"1999","journal-title":"Sens. Actuators A"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/S0924-4247(98)00209-X","article-title":"The determination of the effective ambient temperature for thermal flow sensors in a non-isothermal environment","volume":"72","year":"1999","journal-title":"Sens. Actuators A"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1016\/0924-4247(94)00923-6","article-title":"Multi-parameter detection in fluid flows","volume":"47","author":"Lammerink","year":"1995","journal-title":"Sens. Actuators A"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/S0924-4247(02)00187-5","article-title":"High resolution flow characterization in Bio-MEMS","volume":"100","author":"Ernst","year":"2002","journal-title":"Sens. Actuators A"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/j.flowmeasinst.2008.12.005","article-title":"Micro-flow metering and viscosity measurement of low viscosity Newtonian fluids using a fibreoptical spatial filter technique","volume":"20","author":"Petrak","year":"2009","journal-title":"Flow Meas. Instrum."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"074005","DOI":"10.1088\/0957-0233\/21\/7\/074005","article-title":"Precise micro flow rate measurements by a laser Doppler velocity profile sensor with time division multiplexing","volume":"21","author":"Koenig","year":"2010","journal-title":"Meas. Sci. Technol."},{"key":"ref_15","unstructured":"Richter, M., Wackerle, M., Woias, P., and Hillerich, B. A Novel Flow Sensor with High Time Resolution based on Differential Pressure Principle. Orlando, FL, USA."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/S0924-4247(01)00546-5","article-title":"DP flow sensor using optical fibre Bragg grating","volume":"92","author":"Lim","year":"2001","journal-title":"Sens. Actuators A"},{"key":"ref_17","unstructured":"Boillat, M.A., van der Wiel, A.J., Hoogerwerf, A.C., and de Rooij, N.F. (2, January 29). A Differential Pressure Liquid Flow Sensor for Regulation and Dosing Systems. Amsterdam, The Netherlands."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"015108","DOI":"10.1063\/1.2431794","article-title":"Novel liquid flow sensor based on differential pressure method","volume":"78","author":"Liu","year":"2007","journal-title":"Rev. Sci. Instrum."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1039\/b310282c","article-title":"Microfluidic flow transducer based on the measurement of electrical admittance","volume":"4","author":"Collins","year":"2004","journal-title":"Lab Chip"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1016\/j.sna.2006.10.022","article-title":"Electrokinetic flow meter Sens","volume":"136","author":"Kim","year":"2007","journal-title":"Actuators A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1087","DOI":"10.1109\/JMEMS.2007.906078","article-title":"Electrolytic-bubble-based flow sensor for microfluidic systems","volume":"16","author":"Wang","year":"2007","journal-title":"J. Microelectromech. Syst."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2264","DOI":"10.1088\/0960-1317\/17\/11\/013","article-title":"Fabrication of SU-8 free-standing structures embedded in microchannels for microfluidic control","volume":"17","author":"Ezkerra","year":"2007","journal-title":"J. Micromech. Microeng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.1109\/JMEMS.2005.856650","article-title":"Scalable microbeam flowsensors with electronic readout","volume":"14","author":"Radhakrishnan","year":"2005","journal-title":"J. Micromech. Syst."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1352","DOI":"10.1039\/b706944h","article-title":"Microfluidic flow rate detection based on integrated optical fiber cantilever","volume":"7","author":"Lien","year":"2007","journal-title":"Lab Chip"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"601","DOI":"10.1109\/JSEN.2012.2223667","article-title":"PDMS microcantilever-based flow sensor integration for lab-on-a-chip","volume":"13","author":"Nezhad","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/j.sna.2010.02.002","article-title":"A self-bended piezoresistive microcantilever flow sensor for low flow rate measurement","volume":"158","author":"Zhang","year":"2010","journal-title":"Sens. Actuators A"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"015007","DOI":"10.1088\/0960-1317\/21\/1\/015007","article-title":"Fabrication of a cantilever-based microfluidic flow meter with nL min \u22121 resolution","volume":"21","author":"Noeth","year":"2011","journal-title":"J. Micromech. Microeng."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1903","DOI":"10.1116\/1.2806960","article-title":"Optimized plasma-deposited fluorocarbon coating for dry release and passivation of thin SU-8 cantilevers","volume":"25","author":"Keller","year":"2007","journal-title":"J. Vac. Sci. Technol. B."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"125020","DOI":"10.1088\/0960-1317\/18\/12\/125020","article-title":"Processing of thin SU-8 films","volume":"18","author":"Keller","year":"2008","journal-title":"J. Micromech. Microeng."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"045024","DOI":"10.1088\/0960-1317\/20\/4\/045024","article-title":"Fabrication of thin SU-8 cantilevers: Initial bending, release and time stability","volume":"20","author":"Keller","year":"2010","journal-title":"J. Micromech. Microeng."},{"key":"ref_31","unstructured":"Van Rijn, C.J.M., and Elwenspoek, M.C. (February, January 29). Microfiltration Membrane Sieve with Silicon Micromachining for Industrial and Biomedical Applications. Amsterdam, The Netherlands."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1088\/0957-4484\/9\/4\/007","article-title":"Nanosieves with microsystem technology for microfiltration applications","volume":"9","author":"Veldhuis","year":"1998","journal-title":"Nanotechnology"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1088\/0960-1317\/6\/1\/001","article-title":"LPCVD against PECVD for micromechanical applications","volume":"6","author":"Stoffel","year":"1996","journal-title":"J. Micromech. Microeng."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2297","DOI":"10.1016\/j.mee.2011.02.093","article-title":"Deposition of biopolymer films on micromechanical sensors","volume":"88","author":"Keller","year":"2011","journal-title":"Microelec. Eng."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/14\/1\/229\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:51:35Z","timestamp":1760219495000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/14\/1\/229"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2013,12,23]]},"references-count":34,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2014,1]]}},"alternative-id":["s140100229"],"URL":"https:\/\/doi.org\/10.3390\/s140100229","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2013,12,23]]}}}