Research Areas

Nanomaterials and Devices

Chemical Sensors

Energy Materials

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CHEMICAL SENSORS

Electronic Nose (E-Nose) Sensor Array and Machine Learning-Based Analysis

A major focus of research at IIT Delhi has been the development of next-generation chemiresistive gas sensors and electronic nose (e-nose) systems for the detection of volatile organic compounds (VOCs) relevant to healthcare diagnostics, environmental monitoring, and food quality assessment.
One of the key challenges in VOC sensing is achieving reliable discrimination between analytes in complex mixtures and humidity interference. To address This challenge, we developed machine learning-enabled e-nose systems based on two-dimensional (2D) transition metal dichalcogenides (TMDs), integrating advanced nanomaterial design with data-driven signal processing. A significant contribution was the development of an ultrasensitive WSe₂/MWCNT hybrid electronic nose platform for volatile amine detection (Adv. Funct. Mater. 2025, 35, 2417729).

By engineering heterointerfaces between WSe2 and multi-walled carbon nanotubes, the sensor array achieved enhanced charge transport and analyte interactions for highly sensitive detection of volatile amines. Coupled with machine learning algorithms, the platform demonstrated accurate analyte classification, demonstrating the potential of hybrid nanomaterials for intelligent chemical sensing.
In another study, we developed a site-selective MoS₂-based sensor capable of discriminating triethylamine from structurally similar volatile amines using a single sensor (Adv. Funct. Mater. 2024, 34, 2405232). This work introduced a new way of sensing that combines transient kinetic signatures with machine learning-assisted pattern recognition, instead of using traditional sensor arrays. The underlying technology has resulted in an Indian patent application (No. 202411028211), demonstrating its translational potential.

To address the longstanding challenge of humidity interference in gas sensing, we developed porous SnO₂ nanosheets for room-temperature ammonia detection under extreme humidity conditions (Mater. Horiz., 2024,11, 184-195). Through rational nanostructuring and defect engineering, the sensors exhibited stable performance even under highly humid environments where conventional metal oxide sensors often fail.

Building upon these advances, we further developed a ligand-functionalized WS₂ electronic nose sensor array for the selective detection of oxygenated volatile organic compounds and fruit odor identification (ACS Sensors, 2026). This work introduced a molecular functionalization strategy to create chemically diverse sensing interfaces on a single material platform. To extract complex odor fingerprints, advanced transformer-based deep learning models were employed in collaboration with Prof. Santanu Chaudhury (former professor at Dept. Electrical Engineering, IIT Delhi) for accurate classification of complex VOC mixtures and fruit odor identification.
The work establishes a foundation for next-generation sensing technologies capable of addressing critical challenges in healthcare, environmental sustainability, food quality monitoring, and smart sensing systems.

Team Members

Snehraj Gaur, Divyansh Lalwani, Nidhi Bharti, Rahul Kumar and Varsha R

The project is funded by: ANRF, Core Research Grant (2020-2025)

ENERGY-EFFICIENT DEVICES

Development of Electrochromic Materials for Energy Efficient Windows

Another important thrust of our research has focused on the development of advanced electrochromic smart windows for energy-efficient buildings through nanoscale interface engineering, phase-controlled materials synthesis, and plasmonic enhancement strategies. This work addresses the growing demand for sustainable technologies capable of dynamically regulating solar radiation, reducing building energy consumption, and improving indoor thermal comfort.

A key contribution has been the rational design of mixed-phase tungsten oxide (WO₃) electrochromic materials, where controlled coexistence of orthorhombic and hexagonal phases was exploited to optimize ion transport and electrochromic performance. We developed a low-temperature hydrogen-assisted synthesis strategy enabling precise phase control, resulting in enhanced Li⁺ diffusion, increased density of optically active sites, and improved electrochromic characteristics. The optimized material exhibited high optical modulation (52%), coloration efficiency (133 cm² C⁻¹), rapid switching (<2.7 s), and excellent cycling stability exceeding 5,000 cycles. The formation of phase junctions stabilized structural deformation during ion intercalation, establishing phase engineering as an effective strategy for simultaneously enhancing electrochromic performance, energy-storage capability, and heat-blocking characteristics. (ACS Appl. Mater. Interfaces 2025, 17, 9, 14147).
Building upon these advances, we achieved a significant breakthrough in plasmon-enhanced electrochromism through the integration of anisotropic gold nanostructures with hydrated tungsten oxide. In the study, we demonstrated that morphology-controlled plasmonic interfaces can substantially improve electrochromic performance through localized surface plasmon resonance (LSPR)-mediated enhancement of charge transport and ion diffusion. The optimized Au nanorod/WO₃·H₂O hybrid exhibited outstanding electrochromic performance, including 70% optical modulation in the near-infrared region, high coloration efficiency (172 cm² C⁻¹), and exceptional cycling stability with 99.9% retention over 3,000 cycles. Electrochemical investigations revealed significant improvements in donor density and diffusion kinetics, offering novel insights into plasmon-assisted electrochromic mechanisms. Importantly, the strong near-infrared modulation enabled passive thermal regulation, demonstrating the potential of these materials for next-generation dual-band smart windows capable of reducing cooling loads in buildings. (ACS Appl. Mater. Interfaces 2026, 18, 6, 10046)
In addition to fundamental materials development, we have been focused on scalable and economically viable device fabrication strategies. In another work, we developed a dual-functional electrochromic smart window based on a WO₃–reduced graphene oxide nanocomposite ink spray-coated onto low-cost hybrid electrodes. The device combined electrochromic functionality with energy-storage characteristics while employing solution-processable manufacturing methods suitable for large-area deployment. The use of printable nanocomposite inks and low-cost substrates demonstrated a practical pathway toward commercialisation of smart window technologies. (ACS Appl. Mater. Interfaces 2026, 18, 6, 10046).
The innovation and translational significance of this research were recognised through the selection of our electrochromic smart window technology in the second round of Bharat Innovates-2026 at IIT Mumbai (see the events section for more details).

Collectively, these contributions have advanced the field of electrochromic materials through phase engineering, plasmonic interface design, scalable device fabrication, and the emerging neuromorphic functionalities, creating pathways toward next-generation intelligent and energy-efficient smart window technologies.

Team Members:

Himanshu Nath, Laavanya Singh Malik, Maria Amin, Naman Gupta and Pushpendra Kumar

The project is funded by: DST-Advanced Manufacturing Technologies jointly with JNCASR, Bangalore; CeNS, Bangalore and Hind High Vacuum, Bangalore.

Research Collaborators

International Collaborators

Prof. Hossam Haick, Technion-Israel Institute of Technology, Haifa, Israel (Sensors Development)

Prof. Kotaro Takeyasu, Hokkaido University, Japan (Catalytic In situ Studies)

National Collaborators

Prof. Santanu Chaudhury, Ashoka University (Machine Learning-assisted sensor development)

Prof. Giridhar U. Kulkarni, JNCASR, Bangalore (Electrochromic and Neuromorphic studies)

Dr. Ashutosh Singh, CeNS, Bangalore (Electrochromic materials development)

Dr. Harun Venkateshan, IIT Delhi (Carbon Aerogels)

Dr. Dibyajyoti Ghosh, Materials Engineering, IIT Delhi (DFT calculations)

Research Funding

DST Advanced Manufacturing Technology Grant- DST/TDT/AMT/2021/009 (G) (2022-27)
IIT Delhi Seed Grant ( July 2023-2026)
SERB Core Research Grant- CRG/2020/003465 (2020-24)
SERB Women Excellence Award- WEA/2020/000038 (2021-23)
DRDO CARS (Defense Lab Jodhpur)- DLJ/TC/1025/I/69 (2021-22)
SERB Extra Mural Research Grant- EMR/2016/000785 (2017-2020)
IIT Jodhpur Seed Grant on "Thermochromic Materials for Smart WIndows" (2016-2019)
GIAN Short course- "Advanced Materials and Future Technologies for Solar Energy Conversion"

Jan 2017, Course Instructor: Prof. Mukundan Thelakkat

GIAN Short course - "Materials for Energy Storage Devices",

Dec 2015, Course Instructor: Prof. Timothy S. Fisher

Advanced Materials and Devices (AMDL)

Ritu Gupta's Research Group