{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T13:18:15Z","timestamp":1776172695031,"version":"3.50.1"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,4]],"date-time":"2021-03-04T00:00:00Z","timestamp":1614816000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000781","name":"European Research Council","doi-asserted-by":"publisher","award":["695459"],"award-info":[{"award-number":["695459"]}],"id":[{"id":"10.13039\/501100000781","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Ion-sensitive field-effect transistors (ISFETs) form a high sensitivity and scalable class of sensors, compatible with advanced complementary metal-oxide semiconductor (CMOS) processes. Despite many previous demonstrations about their merits as low-power integrated sensors, very little is known about their noise characterization when being operated in a liquid gate configuration. The noise characteristics in various regimes of their operation are important to select the most suitable conditions for signal-to-noise ratio (SNR) and power consumption. This work reports systematic DC, transient, and noise characterizations and models of a back-end of line (BEOL)-modified foundry-made ISFET used as pH sensor. The aim is to determine the sensor sensitivity and resolution to pH changes and to calibrate numerical and lumped element models, capable of supporting the interpretation of the experimental findings. The experimental sensitivity is approximately 40 mV\/pH with a normalized resolution of 5 mpH per \u00b5m2, in agreement with the literature state of the art. Differences in the drain current noise spectra between the ISFET and MOSFET configurations of the same device at low currents (weak inversion) suggest that the chemical noise produced by the random binding\/unbinding of the H+ ions on the sensor surface is likely the dominant noise contribution in this regime. In contrast, at high currents (strong inversion), the two configurations provide similar drain noise levels suggesting that the noise originates in the underlying FET rather than in the sensing region.<\/jats:p>","DOI":"10.3390\/s21051779","type":"journal-article","created":{"date-parts":[[2021,3,5]],"date-time":"2021-03-05T00:39:07Z","timestamp":1614904747000},"page":"1779","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Sensitivity, Noise and Resolution in a BEOL-Modified Foundry-Made ISFET with Miniaturized Reference Electrode for Wearable Point-of-Care Applications"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5466-9530","authenticated-orcid":false,"given":"Francesco","family":"Bellando","sequence":"first","affiliation":[{"name":"Electronic Department, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2870-2613","authenticated-orcid":false,"given":"Leandro Julian","family":"Mele","sequence":"additional","affiliation":[{"name":"DPIA Department, University of Udine, 33100 Udine, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1672-1166","authenticated-orcid":false,"given":"Pierpaolo","family":"Palestri","sequence":"additional","affiliation":[{"name":"DPIA Department, University of Udine, 33100 Udine, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Junrui","family":"Zhang","sequence":"additional","affiliation":[{"name":"Xsensio SA Batiment A, EPFL Innovation Park, 1015 Lausanne, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adrian Mihai","family":"Ionescu","sequence":"additional","affiliation":[{"name":"Electronic Department, Swiss Federal Institute of Technology Lausanne, 1015 Lausanne, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8688-4326","authenticated-orcid":false,"given":"Luca","family":"Selmi","sequence":"additional","affiliation":[{"name":"DIEF, University of Modena and Reggio Emilia, 41125 Modena, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1021\/acssensors.7b00047","article-title":"Wearable, flexible, and multifunctional healthcare device with an ISFET chemical sensor for simultaneous sweat pH and skin temperature monitoring","volume":"2","author":"Nakata","year":"2017","journal-title":"ACS Sens."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Douthwaite, M., Moser, N., Koutsos, E., Yates, D., Mitcheson, P., and Georgiou, P. 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