{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T05:01:47Z","timestamp":1790744507426,"version":"4.1.0"},"reference-count":38,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,12,13]],"date-time":"2021-12-13T00:00:00Z","timestamp":1639353600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["1842718"],"award-info":[{"award-number":["1842718"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003713","name":"Korea Institute of Materials Science","doi-asserted-by":"publisher","award":["POC2930"],"award-info":[{"award-number":["POC2930"]}],"id":[{"id":"10.13039\/501100003713","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Molybdenum disulfide (MoS2) features a band gap of 1.3 eV (indirect) to 1.9 eV (direct). This tunable band gap renders MoS2 a suitable conducting channel for field-effect transistors (FETs). In addition, the highly sensitive surface potential in MoS2 layers allows the feasibility of FET applications in biosensors, where direct immobilization and detection of biological molecules are conducted in wet conditions. In this work, we report, for the first time, the degradation of chemical vapor deposition (CVD) grown MoS2 FET-based sensors in the presence of phosphate buffer and water, which caused false positive response in detection. We conclude the degradation was originated by physical delamination of MoS2 thin films from the SiO2 substrate. The problem was alleviated by coating the sensors with a 30 nm thick aluminum oxide (Al2O3) layer using atomic layer deposition technique (ALD). This passive oxide thin film not only acted as a protecting layer against the device degradation but also induced a strong n-doping onto MoS2, which permitted a facile method of detection in MoS2 FET-based sensors using a low-power mode chemiresistive I-V measurement at zero gate voltage (Vgate = 0 V). Additionally, the oxide layer provided available sites for facile functionalization with bioreceptors. As immunoreaction plays a key role in clinical diagnosis and environmental analysis, our work presented a promising application using such enhanced Al2O3-coated MoS2 chemiresistive biosensors for detection of HIgG with high sensitivity and selectivity. The biosensor was successfully applied to detect HIgG in artificial urine, a complex matrix containing organics and salts.<\/jats:p>","DOI":"10.3390\/bios11120514","type":"journal-article","created":{"date-parts":[[2021,12,14]],"date-time":"2021-12-14T01:20:41Z","timestamp":1639444841000},"page":"514","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Effect of Al2O3 Passive Layer on Stability and Doping of MoS2 Field-Effect Transistor (FET) Biosensors"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0198-0154","authenticated-orcid":false,"given":"Tung","family":"Pham","sequence":"first","affiliation":[{"name":"Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA 92521, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ying","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA 92521, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jhoann","family":"Lopez","sequence":"additional","affiliation":[{"name":"Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA 92521, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mei","family":"Yang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biorheological Science and Technology Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thien-Toan","family":"Tran","sequence":"additional","affiliation":[{"name":"Department of Bioengineering, University of California Riverside, Riverside, CA 92521, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2831-4154","authenticated-orcid":false,"given":"Ashok","family":"Mulchandani","sequence":"additional","affiliation":[{"name":"Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA 92521, USA"},{"name":"Center for Environmental Research and Technology (CE-CERT), University of California Riverside, Riverside, CA 92507, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"12073","DOI":"10.1021\/acsami.7b00420","article-title":"Bin Centimeter-Scale CVD Growth of Highly Crystalline Single-Layer MoS2 Film with Spatial Homogeneity and the Visualization of Grain Boundaries","volume":"9","author":"Tao","year":"2017","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"666","DOI":"10.1126\/science.1102896","article-title":"Electric Field Effect in Atomically Thin Carbon Films","volume":"306","author":"Novoselov","year":"2004","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1333","DOI":"10.1021\/nn3049158","article-title":"Band gap engineering of chemical vapor deposited graphene by in situ BN doping","volume":"7","author":"Chang","year":"2013","journal-title":"ACS Nano"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"7803","DOI":"10.1021\/jacs.8b02209","article-title":"Bandgap Engineering of Graphene Nanoribbons by Control over Structural Distortion","volume":"140","author":"Hu","year":"2018","journal-title":"J. Am. Chem. Soc."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"3766","DOI":"10.1021\/cr300263a","article-title":"Graphene-Like Two-Dimensional Materials","volume":"113","author":"Xu","year":"2013","journal-title":"Chem. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1038\/nnano.2010.279","article-title":"Single-layer MoS2 transistors","volume":"6","author":"Radisavljevic","year":"2011","journal-title":"Nat. Nanotechnol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1016\/j.bios.2018.09.069","article-title":"Affinity sensor for haemoglobin A1c based on single-walled carbon nanotube field-effect transistor and fructosyl amino acid binding protein","volume":"129","author":"Hatada","year":"2019","journal-title":"Biosens. Bioelectron."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1016\/j.carbon.2018.10.079","article-title":"MoS2-graphene heterostructures as efficient organic compounds sensing 2D materials","volume":"142","author":"Pham","year":"2019","journal-title":"Carbon N. Y."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1016\/j.bios.2018.09.041","article-title":"A paper-based chemiresistive biosensor employing single-walled carbon nanotubes for low-cost, point-of-care detection","volume":"130","author":"Shen","year":"2019","journal-title":"Biosens. Bioelectron."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1016\/j.bios.2018.11.049","article-title":"Graphene nanogap electrodes in electrical biosensing","volume":"126","author":"Ramnani","year":"2019","journal-title":"Biosens. Bioelectron."},{"key":"ref_11","unstructured":"Hossain, M., Sanaullah, M., Yousuf, A.H.B., Es-Saki, A., and Chowdhury, M.H. (2015, January 2\u20135). Analytical analysis of the contact resistance (Rc) of metal-MoS2 interface. Proceedings of the 2015 IEEE 58th International Midwest Symposium on Circuits and Systems, Fort Collins, CO, USA."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"6292","DOI":"10.1021\/acsnano.8b03331","article-title":"Schottky Barrier Height Engineering for Electrical Contacts of Multilayered MoS2 Transistors with Reduction of Metal-Induced Gap States","volume":"12","author":"Kim","year":"2018","journal-title":"ACS Nano"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2340","DOI":"10.1007\/s12274-015-0744-8","article-title":"Field-effect transistor with a chemically synthesized MoS2 sensing channel for label-free and highly sensitive electrical detection of DNA hybridization","volume":"8","author":"Lee","year":"2015","journal-title":"Nano Res."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Nam, H., Oh, B.R., Chen, P., Chen, M., Wi, S., Wan, W., Kurabayashi, K., and Liang, X. (2015). Multiple MoS2 transistors for sensing molecule interaction kinetics. Sci. Rep., 5.","DOI":"10.1038\/srep10546"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"12115","DOI":"10.1021\/acsnano.5b05173","article-title":"Controlled Doping of Vacancy-Containing Few-Layer MoS2 via Highly Stable Thiol-Based Molecular Chemisorption","volume":"9","author":"Sim","year":"2015","journal-title":"ACS Nano"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1385","DOI":"10.1002\/adfm.201102111","article-title":"From bulk to monolayer MoS2: Evolution of Raman scattering","volume":"22","author":"Li","year":"2012","journal-title":"Adv. Funct. Mater."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Jahangir, I., Koley, G., and Chandrashekhar, M.V.S. (2017). Back gated FETs fabricated by large-area, transfer-free growth of a few layer MoS2 with high electron mobility. Appl. Phys. Lett., 110.","DOI":"10.1063\/1.4982595"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Guo, Y., Wei, X., Shu, J., Liu, B., Yin, J., Guan, C., Han, Y., Gao, S., and Chen, Q. (2015). Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors. Appl. Phys. Lett., 106.","DOI":"10.1063\/1.4914968"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Illarionov, Y.Y., Waltl, M., Di Bartolomeo, A., Genovese, L., Illarionov, Y.Y., Rzepa, G., Waltl, M., Knobloch, T., and Grill, A. (2016). The role of charge trapping in MoS2\/SiO2 and MoS2\/hBN field-effect transistors \u201cThe role of charge trapping in MoS2\/SiO2 and MoS2\/hBN field-effect transistors\u201d. 2D Mater., 3.","DOI":"10.1088\/2053-1583\/3\/3\/035004"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3992","DOI":"10.1021\/nn5009148","article-title":"MoS2 Field-Effect Transistor for Next-Generation Label-Free Biosensors","volume":"8","author":"Sarkar","year":"2014","journal-title":"ACS Nano"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"7942","DOI":"10.1039\/C7RA13614E","article-title":"High sensitivity glucose detection at extremely low concentrations using a MoS2-based field-effect transistor","volume":"8","author":"Shan","year":"2018","journal-title":"RSC Adv."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Ahn, J.H., Parkin, W.M., Naylor, C.H., Johnson, A.T.C., and Drndi\u0107, M. (2017). Ambient effects on electrical characteristics of CVD-grown monolayer MoS2 field-effect transistors. Sci. Rep., 7.","DOI":"10.1038\/s41598-017-04350-z"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Jung, C., Yang, H.I., and Choi, W. (2019). Effect of Ultraviolet-Ozone Treatment on MoS2 Monolayers: Comparison of Chemical-Vapor-Deposited Polycrystalline Thin Films and Mechanically Exfoliated Single Crystal Flakes. Nanoscale Res. Lett., 14.","DOI":"10.1186\/s11671-019-3119-3"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"11522","DOI":"10.1021\/nn5057673","article-title":"Surface-energy-assisted perfect transfer of centimeter-scale monolayer and few-layer MoS2 films onto arbitrary substrates","volume":"8","author":"Gurarslan","year":"2014","journal-title":"ACS Nano"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"10677","DOI":"10.1039\/C6NR01118G","article-title":"Large-scale arrays of single- and few-layer MoS2 nanomechanical resonators","volume":"8","author":"Jia","year":"2016","journal-title":"Nanoscale"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.matchemphys.2015.03.041","article-title":"Gold nanoparticles on MoS2 layered crystal flakes","volume":"158","author":"Cao","year":"2015","journal-title":"Mater. Chem. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1154","DOI":"10.1007\/s40843-018-9233-9","article-title":"Optical visualization of MoS2 grain boundaries by gold deposition","volume":"61","author":"Sun","year":"2018","journal-title":"Sci. China Mater."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"7447","DOI":"10.1021\/acsami.6b14805","article-title":"Shape-Controllable Gold Nanoparticle-MoS2 Hybrids Prepared by Tuning Edge-Active Sites and Surface Structures of MoS2 via Temporally Shaped Femtosecond Pulses","volume":"9","author":"Zuo","year":"2017","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"7307","DOI":"10.1021\/acs.nanolett.5b02559","article-title":"Highly Sensitive, Encapsulated MoS2 Photodetector with Gate Controllable Gain and Speed","volume":"15","author":"Kufer","year":"2015","journal-title":"Nano Lett."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"28130","DOI":"10.1021\/acsami.6b07271","article-title":"Effect of Al2O3 Deposition on Performance of Top-Gated Monolayer MoS2-Based Field Effect Transistor","volume":"8","author":"Song","year":"2016","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"319","DOI":"10.1016\/j.vacuum.2016.07.013","article-title":"Structure and properties of Al2O3 thin films deposited by ALD process","volume":"131","author":"Lukaszkowicz","year":"2016","journal-title":"Vacuum"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Woo, W.J., Seo, S., Nam, T., Kim, Y., Kim, D., Song, J.G., Oh, I.K., Lim, J.H., Kim, H.J., and Kim, H. (2021). MoS2 doping by atomic layer deposition of high-k dielectrics using alcohol as process oxidants. Appl. Surf. Sci., 541.","DOI":"10.1016\/j.apsusc.2020.148504"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Valsaraj, A., Chang, J., Rai, A., Register, L.F., and Banerjee, S.K. (2015). Theoretical and experimental investigation of vacancy-based doping of monolayer MoS2 on oxide. 2D Mater., 2.","DOI":"10.1088\/2053-1583\/2\/4\/045009"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"7962","DOI":"10.1021\/acs.nanolett.7b04374","article-title":"Sulfur Adatom and Vacancy Accelerate Charge Recombination in MoS2 but by Different Mechanisms: Time-Domain Ab Initio Analysis","volume":"17","author":"Li","year":"2017","journal-title":"Nano Lett."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"7093","DOI":"10.1039\/C6TC01746K","article-title":"Repairing sulfur vacancies in the MoS2 monolayer by using CO, NO and NO2 molecules","volume":"4","author":"Ma","year":"2016","journal-title":"J. Mater. Chem. C"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Lu, H., Kummel, A., and Robertson, J. (2018). Passivating the sulfur vacancy in monolayer MoS2. APL Mater., 6.","DOI":"10.1063\/1.5030737"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1046\/j.1472-765X.1997.00378.x","article-title":"A simple artificial urine for the growth of urinary pathogens","volume":"24","author":"Brooks","year":"1997","journal-title":"Lett. Appl. Microbiol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3196","DOI":"10.1021\/acsnano.8b08778","article-title":"MoS2-Based Optoelectronic Gas Sensor with Sub-parts-per-billion Limit of NO2 Gas Detection","volume":"13","author":"Pham","year":"2019","journal-title":"ACS Nano"}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/11\/12\/514\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:46:44Z","timestamp":1760168804000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/11\/12\/514"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,13]]},"references-count":38,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2021,12]]}},"alternative-id":["bios11120514"],"URL":"https:\/\/doi.org\/10.3390\/bios11120514","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,12,13]]}}}