Effects of graphene layer and gold nanoparticles on sensitivity of humidity sensors

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Bao, Jiawei
Hashemi, Niloofar
Guo, Jingshuai
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SAGE Publications
Hashemi, Nicole
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Mechanical Engineering
The Department of Mechanical Engineering at Iowa State University is where innovation thrives and the impossible is made possible. This is where your passion for problem-solving and hands-on learning can make a real difference in our world. Whether you’re helping improve the environment, creating safer automobiles, or advancing medical technologies, and athletic performance, the Department of Mechanical Engineering gives you the tools and talent to blaze your own trail to an amazing career.
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Biomedical Sciences

The Department of Biomedical Sciences aims to provide knowledge of anatomy and physiology in order to understand the mechanisms and treatment of animal diseases. Additionally, it seeks to teach the understanding of drug-action for rational drug-therapy, as well as toxicology, pharmacodynamics, and clinical drug administration.

The Department of Biomedical Sciences was formed in 1999 as a merger of the Department of Veterinary Anatomy and the Department of Veterinary Physiology and Pharmacology.

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  • College of Veterinary Medicine (parent college)
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Ames National Laboratory

Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.

For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.

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Bioeconomy Institute
The Bioeconomy Institute at Iowa State University leads the nation and world in establishing the bioeconomy, where society obtains renewable fuel, energy, chemicals, and materials from agricultural sources. The institute seeks to advance the use of biorenewable resources for the production of fuels, energy, chemicals, and materials. The Institute will assure Iowa’s prominence in the revolution that is changing the way society obtains its essential sources of energy and carbon. This revolution will dramatically reduce our dependence on petroleum. Instead of fossil sources of carbon and energy, the bioeconomy will use biomass (including lignocellulose, starches, oils and proteins) as a renewable resource to sustain economic growth and prosperity. Agriculture will supply renewable energy and carbon to the bioeconomy while engineering will transform these resources into transportation fuels, commodity chemicals, and electric power. This transformation, however, must be done in a manner that meets our present needs without compromising those of future generations.
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Humidity sensors can be used to monitor body sweat. Here, we studied a humidity sensor that comprised of a graphene layer between two electrodes. The operating principle is that the humidity sensor will respond when vapor reaches the graphene layer from the top. Based on the humidity diffusion, the sensor measures the relative humidity (RH) with different response times. Graphene is a material with high diffusivity and small thickness that can increase the sensitivity of a sensor. Based on the micro electro mechanical systems (MEMS) method, we modeled the humidity sensor using COMSOL Multiphysics® transport of diluted species software. Additionally, we used the concentration values from the simulations to determine the relationship between capacitance and relative humidity. The sensitivity was found to be 3.379 × 10−11 pF/%RH for the 4-layer graphene, 1.210 × 10−14 pF/%RH for the 8-layer graphene, and 3.597 × 10−11 pF/%RH for the 16-layer graphene sensor. The sensitivity of 4-layer graphene with gold sensor is 3.872 × 10−13 pF/%RH which is smaller than 4-layer graphene sensor, and graphene with gold nanoparticles shows better response time than 4-layer graphene sensor.
This is a manuscript of an article published as Bao, Jiawei, Niloofar Hashemi, Jingshuai Guo, and Nicole N. Hashemi. "Effects of graphene layer and gold nanoparticles on sensitivity of humidity sensors." Journal of Micromanufacturing 3, no. 1 (2020): 20-27. DOI: 10.1177%2F2516598419896130. Copyright 2020 The Authors. Reprinted by permission of SAGE Publications.