Continuous, real-time monitoring and identification of bacteria through detection of microbially emitted volatile molecules are highly sought albeit elusive goals. We introduce an artificial nose for sensing and distinguishing vapor molecules, based upon recording the capacitance of interdigitated electrodes (IDEs) coated with carbon dots (C-dots) exhibiting different polarities. Exposure of the C-dot-IDEs to volatile molecules induced rapid capacitance changes that were intimately dependent upon the polarities of both gas molecules and the electrode-deposited C-dots. We deciphered the mechanism of capacitance transformations, specifically substitution of electrode-adsorbed water by gas molecules, with concomitant changes in capacitance related to both the polarity and dielectric constants of the vapor molecules tested. The C-dot-IDE gas sensor exhibited excellent selectivity, aided by application of machine learning algorithms. The capacitive C-dot-IDE sensor was employed to continuously monitor microbial proliferation, discriminating among bacteria through detection of distinctive “volatile compound fingerprint” for each bacterial species. The C-dot-IDE platform is robust, reusable, readily assembled from inexpensive building blocks and constitutes a versatile and powerful vehicle for gas sensing in general, bacterial monitoring in particular.

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Sniffing Bacteria with a Carbon-Dot Artificial Nose.

Smart and Intelligent E‐nose for Sensitive and Selective Chemical Sensing Applications

Electronic Nose and Tongue Materials for Sensing

https://iopscience.iop.org/article/10.1088/1361-6439/aad507/pdf

Development of scalable planar MEMS technology for low power operated ethanol sensor

Sensing Materials: Electronic Nose and Tongue Materials

This paper presents the selective and highly sensitive performance of porous TiO2/nano-Si heterostructure for ethanol sensing. The fabrication steps involved were scalable and reproducible making the device eligible for batch fabrication suitable for industry production. The sensor response was recorded as a change in resistance upon exposure to a variety of organic vapors in the concentration range of 5–500 ppm and in simulated real breath conditions. Although the response was obtained at room temperature, however, the operating temperature of the sensor was found to be around 100 °C. The sensing mechanism has been explained on the basis of adsorption–desorption theory of gases, physical, and chemical properties of the materials. A prototype was built for complete realization of the sensor. The sensor data from the sensor array comprising of hetersostructure and its single-layer counterparts were collated and signal conditioning like Regression model and PCA was done. These were used for assessing the alcohol concentration and separation of analytes for the development of E-nose system.

Monika Agrawal

Papers

Interfacial Engineering in TiO 2 /Nano-Si Heterostructure-Based Device Prototype for E-Nose Application