Location: Sustainable Water Management Research
Project Number: 6066-13000-006-012-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2021
End Date: Aug 31, 2024
Objective:
The goal of this project is to develop an electrochemical sensor array with nanoengineered membranes to characterize nitrous oxide, methane, and carbon dioxide levels in the atmosphere directly above agricultural fields. The sensor array will be deployed as part of a wireless sensing network to monitor greenhouse gas emissions. The project will design, create, and evaluate a library of functionally diverse materials for selection and integration into electrochemical sensor arrays. A version of the sensing system will also be developed to measure ammonia gas.
Approach:
An electrochemical sensor array will be constructed using nanoengineered membranes with selective permeability to generate unique sensor responses to allow for the characterization of nitrous oxide, methane, and carbon dioxide levels. A library of functionally diverse materials will be evaluated for selection and integration into the electrochemical sensor arrays. These arrays will be fabricated on top of electrodes on either glass or flexible substrates that allow for individually addressable responses to each greenhouse gas of interest. Fabrication of the methane and carbon dioxide sensors will start with patterning of photoresist on glass or flexible substrate as a protective mold prior to the deposition of gold for the working electrode and counter electrode. The surface of the working electrode will be selectively coated with multi wall carbon nanotubes (MWCNT) or platinum nanoparticles by electrodeposition. A thin layer of silver will be selectively deposited to form the reference electrode by using the photoresist mold. The silver electrode will be uniformly chlorinated with a buffer solution to overcoat the nanoparticles. MWCNT or nanoparticles on the surfaces of the electrodes drastically increase surface area for high efficiency electrochemical sensing. Fabrication of the nitrous oxide sensor will be started with patterning of resistive heater and platinum electrode on glass. YSZ (Yttria stabilized zirconia) will be placed on top of the patterns and another platinum electrode will be formed on top. The resistive heater will be localized heated on demand to elevate temperature in a confined space up to 700°C. Nitrous oxide gas in air will be fed into the sensor and the elevated temperatures will remove common oxygen components and leave only oxygen gas from N2O which can be amperometrically detected for diffusion of oxygen through YSZ.
The fabricated sensors will be integrated into a wireless remote sensing network. The performance of the experimental sensors will be evaluated against commercial sensors when deployed in an agricultural field.
