2026-09-21T11:52:36Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/34249 2023-07-10 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

Liu, Gang Logan Gorti, Tejaswi 2012-09-18T21:07:52Z 2012-09-18T21:07:52Z 2012-08 2012-09-18T21:07:52Z 2012-08 In biological and environmental applications, it is desirable to be able to measure hydrogen and hydroxyl ion concentrations (pH levels). Conventionally, the measurement processes take a considerable amount of time involving several calibration steps and handling of fragile electrodes. Here we propose a new, more robust and theoretically reliable way of sensing pH. Following a similar approach to Dr. Qingjun Liu’s work on the light-addressable potentiometric sensor (LAPS) from the Zhejiang University in China, we fabricated a silicon pH sensor, with polydimethylsiloxane (PDMS) fluidic channels for solution delivery and testing. Particularly for biological and environmental applications, the range of pH sensing is confined to 6 to 8. The fabricated device used n-type silicon, so only five acidic solutions between pH 5 and pH 7 were tested. Device test results proved to be somewhat problematic. We were not able to obtain consistent capacitance measurements for a particular pH solution. For some solutions we had extremely large variances in capacitance, yielding “noisy” measurements. However, in retrospect, there are many improvements that could be made to our device and testing procedure in order to obtain more consistent capacitance readings, closer to the theoretical performance. Such changes include modifying the geometry of the electrode which supplies an AC signal for capacitance measurements, and ensuring airtight (PDMS) bonding with the device substrate, guaranteeing seamless solution delivery to the test chamber. It is our hope that future students are able to build upon these results and create a better, more reliable device. Item withdrawn by Katherine Eriksen (eriksen3@illinois.edu) on 2012-07-10T15:47:56Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Gorti_Tejaswi.docx: 4626941 bytes, checksum: a1f17b40bc62b0399f042455e3867ba9 (MD5) Gorti_Tejaswi.pdf: 1882375 bytes, checksum: 2bd4c9199cdbcbca002f7be0e1f92e4c (MD5) Made available in DSpace on 2012-09-18T21:07:52Z (GMT). No. of bitstreams: 3 Gorti_Tejaswi.pdf: 1882375 bytes, checksum: 2bd4c9199cdbcbca002f7be0e1f92e4c (MD5) license.txt: 4061 bytes, checksum: c0b1ee9cd5799a197741a251445b57e1 (MD5) Gorti_Tejaswi.docx: 4626941 bytes, checksum: a1f17b40bc62b0399f042455e3867ba9 (MD5) http://hdl.handle.net/2142/34249 en Copyright 2012 Tejaswi Gorti Silicon semiconductor fabrication solid state device physics biosensors nanotechnology microfluidics pH carrier transport Metal-Oxide-Silicon (MOS) capacitor Silicon-based pH sensor for biological and environmental applications Electrical & Computer Eng 1933 Electrical & Computer Engr 1200 University of Illinois at Urbana-Champaign Thesis M.S. MS:Electr & Computer Eng-UIUC 10KS1200MS