"The work will teach you how to do it" - an old Chinese proveb

Current research focus

1. Industrial chemical sensing & emissions monitoring
We use TDLS to develop high-sensitivity detection platforms for industrial safety applications and for ambient air quality monitoring that are both essential components of sustainable development. We develop accurate, portable and robust systems for long-term and automated measurement systems based on near-IR and mid-IR wavelength modulation spectroscopy (WMS).

 

2. Microbial growth studies
We are especially fascinated by the application of TDLS for non-invasive, time-resolved measurement of bacterial growth by by measuring the CO2 emitted by the bacteria. We are also interested in studying studying the the relation between the various growth stages and the emission of multiple gases, the expression of some interesting microbial traits such as bioluminescence. We have also shown that it is possible to detect at a very early stage, the suppression of growth due to the addition of antibiotics.

 

3. Fiber Bragg grating-based biomedical diagnostics Fiber Bragg gratings are very sensitive to strain (and temperature), and can therefore be used to measure very small bends and vibrations. By measuring the bend angle of fingers one can quantify the extent of recovery during the recovery phase of conditions such a stroke.

4. Bio-sensing using functionalized gold nanorods
We use gold nanorods (AuNRs) with widely tunable localized surface plasmon resonance (LSPR) to design optical bio-sensing platforms. The AuNRs are grown in-house using a low-cost and highly reliable technique. Such plasmonic detection platforms can then be coupled with the TDLS interrogation technique to detect extremely  small spectral shifts of the LSPR induced by the analyte.

Funded projects 

1. UAV-based laser spectroscopic monitoring of greenhouse gas emissions in urban and rural India

    Funding agency: Royal Academy of Engineering (RAE), United Kingdom   

    Project value     : GBP 10,000       

    Role                     : Principal Investigator

    Partners             : Prof Ken Grattan (City University London, UK

    

2. Novel laser-based monitoring of key environmental parameters – addressing well-being, livelihood and a healthier environment in developing regions of India 

   Funding agency: Royal Academy of Engineering (RAE), United Kingdom   

    Project value     : GBP 80,000       

    Role                     : Principal Investigator

    Partners             : Prof Ken Grattan (City University London, UK

3. High-sensitivity detection of atmospheric pollutant gases to monitor the effects on industrial emissions on urban air quality, 
    Funding agency : Gujarat Council for Science and Technology (GUJCOST), Gujarat, India 
    Project value.     : INR 46,39,20

    Status                : approved (2019-2022)
    Role                   : Principal Investigator 

Completed projects 

1. Early Career Fellowship

    Funding agency: IIT Gandhinagar

    Project value     : Rs 12 lakh

    Role                   : Principal Investigator

    Partners            : Dr Ramya S

2. Development of a fiber-optic sensor network to monitor hazardous gas leaks in industrial plants   

    Funding agency: Royal Academy of Engineering (RAE), United Kingdom   

    Project value     : GBP 50,000       

    Role                  : Principal Investigator

    Partners            : Prof Ken Grattan (City University London, UK

3. Development of smart, environment friendly and low-cost fire detection and suppression system
    Project value     : Rs 3,73,00,000
    Status                : completed (2016-2019)
    Role                   : co-Principal Investigator
 

4. Real-time concentration measurement of methane, water vapour, carbon dioxide and carbon monoxide in ethanol auto-thermal reforming using tunable diode laser spectroscopy
    Funding agency : Science and Engineering Research Board, DST, India (SERB)
    Project value      : INR 73,07,000
    Role                    : Principal Investigator
    Partners              : Prof Atul Bhargav, Mechanical Engineering, IIT Gandhinagar
 

5. Quantitative near- and mid-infrared wavelength modulation spectroscopy for gas sensing applications
    Funding agency : Science and Engineering Research Board (SERB), DST, India,  
    Project value      : INR 54,88,700
    Role                    : Principal Investigator
 

6. Development of algorithm for concentration/pressure/temperature measurement of a gas using wavelength modulation spectroscopy
    Funding agency : Defense Electromedical and Biomedical Electronics Laboratory (DEBEL),
                                  Defense Research and Development Organization (DRDO), Bangalore, India
    Project value      : Rs 9,94,000
    Status                 : completed

Collaborators

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Dr Chinmay Ghoroi, Chemical Engg, IITGN

Dr Saumyakanti Khatua,

Chemistry, IITGN

Prof Ken Grattan, City, University of London

Dr Ralf Bauer, EEE, University of Strathclyde

Dr Michael Lengden, EEE, University of Strathclyde

Dr Atul Bhargav, Mechanical Engg, IITGN

Detection technique

We make extensive use of tunable diode laser spectroscopy (TDLS). TDLS uses narrow linewidth semiconductor lasers for accurate recovery of the absolute rotational-vibrational absorption lines of gases. The rotational-vibrational absorption lines of gases have embedded in them information about the concentration, pressure and temperature of the gas. Accurate absorption line shape recovery is therefore the most direct way of estimating these quantities. TDLS with wavelength modulation, known as wavelength modulation spectroscopy (WMS) is a high resolution spectroscopic method of making simultaneous, absolute quantitative measurements of several parameters (pressure, concentration and temperature) of gases. TDLS is very widely used in a large number of harsh industrial environments such as process control, in which efficiency and safety cannot be compromised. The growth of TDLS has been greatly fuelled by the development of compact, low-power, widely tunable, narrow-linewidth and frequency-agile tunable near-infrared and mid-infrared semiconductor lasers. The wide availability of mid-infrared quantum cascade lasers has been a telling factor in the extremely rapid progress of the field of chemical sensing. WMS with 1f and 2f detection affords very high detection sensitivity (ppm, ppb, ppt), very high selectivity and the capability to multiplex several lasers to remotely and continuously monitor vast areas and sensitive installations in real-time. Recent research has led to the development of calibration-free measurement 1f and 2f WMS techniques that have tremendously increased the potency of the technique as regards field applications where one does not have the luxury of periodically re-calibrating the measurement system. Our group currently focuses on developing calibration-free 1f and 2f WMS techniques and applying these to various semiconductor lasers. TDLS systems are compact, have low power requirement, are easy to reconfigure for multiple gases, and can be readily interfaced to electronics and communications systems. The portability of these systems makes field-deployable either in the form of fixed installations or mounted on unmanned land-based or airborne vehicles. Measurements can be done in real-time with fast embedded electronics that allows compact, portable systems to be developed for use in industrial applications as well as in cross-disciplinary research that may involve field measurements.