Research

I have been working in the area of microsensors development. We design, fabricate and characterize various sensors. We also develop the interface electronics and build microsystems for various societal and strategic applications.

Piezoelectric Micromachined Ultrasonic Transducers (PMUT)

PMUTs offer several advantages over conventional transducer technologies. Highly integrated systems can also be developed due to the compatibility of PMUTs with complementary metal-oxide-semiconductor (CMOS) processes, which enables the integration of transducer arrays with on-chip electronics. PMUTs also exhibit a wider bandwidth, making it possible for the ultrasonic waves to be transmitted and received over a broader range of frequencies. Compared to conventional piezoelectric sensors and transducers, PMUTs have achieved reduced noise levels, and low power consumption owing to their small sizes. They can be fabricated using conventional micromachining techniques. These benefits have led to the widespread utilization of MEMS technology for ultrasonic sensors and actuators.

FET-based pH Sensors (ISFET and EGFET)

ISFETs are potentiometric sensors where the ion-sensing membrane is directly incorporated over the gate area of a field-effect transistor (FET). FET is a solid-state active device that exhibits high-input impedance and low-output impedance, which is suitable to study charge accumulation over the gate oxide and transducing it to a measurable electrical current due to the modulation of conducting channel at the semiconductor–oxide interface. The advantage of ISFETs are numerous, such as CMOS compatibility, low power, quick response, miniaturization, and easier integration with readout circuit. The basic application of such devices is to measure the pH of a solution. However, much research has been carried out to measure the concentration of other chemical species such as ions as well as charged molecules. The applications of ISFETs have been extended to several areas, such as environmental monitoring, biomedical diagnosis, agriculture, manufacturing industries, food-quality monitoring, wearable sensors, etc.

MEMS Accelerometers

With the advancement of Micro-Electro-Mechanical Systems (MEMS) technology, MEMS accelerometers are now commercially available and it is now possible to integrate them into cost-sensitive commercial devices such as smartphones, shock monitoring equipment, robotics etc. Due to miniaturization, they can be used for applications such as active stabilization of pictures in cameras, in-vivo activity monitoring in biomedical applications, monitoring mechanical shock and vibration of devices during transportation, etc. They can also have several military applications where high-sensitivity accelerometers along with gyroscopes can act as crucial components in navigation and guidance systems. MEMS accelerometers have low cost, small size, low power consumption, repeatability, high sensitivity and enormous design flexibility.

Capacitive Micromachined Ultrasonic Transducers (CMUT)

Micromachined ultrasound transducers (MUTs) have become indispensable tools across various fields such as medical diagnostics, scientific research, military applications, and non-destructive evaluation due to their small size, low power operation and fast response time. CMUTs provide advantages, such as high directivity, large immersion bandwidth, low-cost manufacturing, easy integration with the integrated circuits (IC) and wide working temperature range, making them a good choice for ultrasonic applications. These transducers rely on high-power driver circuits for pulse generation at specific frequencies, and corresponding receiver circuits to detect and convert incoming ultrasonic signals into electrical equivalents.

MEMS-based Thermopiles

Among the various technologies available for IR sensing, thermopile-based detectors have garnered significant attention due to their high sensitivity and versatility. Operating on the principle of the Seebeck effect, thermopile arrays offer enhanced capabilities for capturing IR radiation and translating it into measurable electrical signals. By leveraging microfabrication techniques, these arrays can be seamlessly integrated into compact yet high-performance sensor systems.