A pinboard by
Shuvashis Dey

PhD Student, Monash University

Research Affiliate, Massachusetts Institute of Technology (MIT)


Design of low cost RFID based sensors for agriculture, infrastructural health monitoring and retail.

The core objective of my research is to develop inexpensive, compact and printable electromagnetic (EM) transduction based passive chipless RFID tag sensor nodes for a specified set of Internet of Things (IoT) application areas. The main application sectors being addressed include retail and supply chain, infrastructural health monitoring and precision agriculture. These sectors have a burning requirement of low cost sensing and item tagging devices. However, due to the absence of such devices, these applications areas do not receive enough traction in terms of industrial applications. My research involves the development of such low cost devices to monitor temperature in perishable food items and environment, soil moisture and salinity contents as well as crack in public infrastructure.

I developed a number of extremely low cost passive sensors that can monitor several environmental parameters. The chipless RFID based soil moisture and salinity sensor designed on polymer substrates offers the ability to detect the moisture and salt content in soil even at a depth of 5 cm from the top surface. This sensor would certainly facilitate farmers and soil scientists to have an inexpensive solution for moisture detection and hence enable a mass deployment of the sensor in agricultural lands. Another sensor developed as a part of my research is the smart skin crack sensor. This sensor has the ability to detect the development and growth of crack at any portion of its surface. Based on this prototype, we envisage a crack sensing scheme that would use conductive paint on walls as the sensor. I also devised a temperature sensor that can resolve the low temperature monitoring issue in retail and supply chain.

Chipless RFID sensors have ample benefits over traditional sensors because of their lower cost, lightweight, robustness and lower radiated power. The abolition of battery and IC provides this type sensor a maintenance free lifelong operation. Due to their potential benefits, my designed sensors have a great promise to penetrate different sectors including agriculture, retail, and structural health monitoring (SHM). This solid prospect with significant commercial potentials ensure that my research outcomes would enable these IoT application areas to attract a far more increased market adoption. Hence, the low cost item tagging and sensing solutions are sure to open up a new horizon in IoT.


Flexible Graphene-Based Wearable Gas and Chemical Sensors

Abstract: Wearable electronics is expected to be one of the most active research areas in the next decade; therefore, nanomaterials possessing high carrier mobility, optical transparency, mechanical robustness and flexibility, lightweight, and environmental stability will be in immense demand. Graphene is one of the nanomaterials that fulfill all these requirements, along with other inherently unique properties and convenience to fabricate into different morphological nanostructures, from atomically thin single layers to nanoribbons. Graphene-based materials have also been investigated in sensor technologies, from chemical sensing to detection of cancer biomarkers. The progress of graphene-based flexible gas and chemical sensors in terms of material preparation, sensor fabrication, and their performance are reviewed here. The article provides a brief introduction to graphene-based materials and their potential applications in flexible and stretchable wearable electronic devices. The role of graphene in fabricating flexible gas sensors for the detection of various hazardous gases, including nitrogen dioxide (NO2), ammonia (NH3), hydrogen (H2), hydrogen sulfide (H2S), carbon dioxide (CO2), sulfur dioxide (SO2), and humidity in wearable technology, is discussed. In addition, applications of graphene-based materials are also summarized in detecting toxic heavy metal ions (Cd, Hg, Pb, Cr, Fe, Ni, Co, Cu, Ag), and volatile organic compounds (VOCs) including nitrobenzene, toluene, acetone, formaldehyde, amines, phenols, bisphenol A (BPA), explosives, chemical warfare agents, and environmental pollutants. The sensitivity, selectivity and strategies for excluding interferents are also discussed for graphene-based gas and chemical sensors. The challenges for developing future generation of flexible and stretchable sensors for wearable technology that would be usable for the Internet of Things (IoT) are also highlighted.

Pub.: 06 Sep '17, Pinned: 31 Oct '17

Real-world testbed for multi-tag UWB chipless RFID system based on a novel collision avoidance MAC protocol

Abstract: Chipless radio frequency identification (RFID) tags are dummy, memoryless, with limited number of bits, very low backscattered power, and short reading range. Therefore, the existing RFID standards and protocols designed for the chipped RFID systems are not applicable for the chipless systems. Main objective of this contribution is to introduce a novel real-world testbed for multi-tag ultra-wideband (UWB) chipless RFID system. In this testbed, a new Notch Position Modulation scheme is implemented as the first medium access control algorithm for handling the multi-tag identification scenario of the frequency signature based chipless RFID tags. This intelligent Notch Position Modulation algorithm reduces the sensing and identification time and accordingly the overall system latency. The proposed protocol enables fetching the frequency signatures of the chipless RFID tags through the whole UWB range effectively. Moreover, an advanced signaling scheme is designed for the RFID reader in order to make the best use of the Federal Communications Commission UWB regulations for increasing the maximum transmitted power and the corresponding reading range. The signaling scheme, real-time channel estimation, and clutter removal technique are implemented on the software defined radio platform in a heavily dense multipath indoor environment. Based on the medium access control protocol, the mitigation of the undesired environmental reflections as well as the interference between the chipless RFID tags is well demonstrated in the developed testbed.

Pub.: 12 Oct '16, Pinned: 31 Oct '17

Adaptive spectrum scanning techniques for reducing the identification time of the frequency coded chipless RFID system

Abstract: The main objective of this contribution is to introduce novel techniques for reducing the time taken from the reader to identify the frequency coded chipless radio frequency identification tags existed in the reader's interrogation region, system latency. The frequency scanning methodology, number of averaging for clutter removal, and hop duration are the 3 main parameters that significantly affect the overall system latency. Consequently, the adaptive frequency hopping (AFH) and adaptive sliding window (ASW) methodologies are proposed and proofed to be efficient for the chipless radio frequency identification systems from the latency and accuracy perspectives. Likewise, the performance of the designed AFH and ASW techniques are compared with the classical fixed frequency hopping methodology with a fine frequency step to validate the accuracy of the proposed methods. Moreover, 4 different coded frequency coded chipless tags are manufactured and used in the measurements. A real-world testbed is designed including a software-defined radio platform by which the proposed adaptive algorithms and traditional fixed frequency hopping methodology are implemented. All the measurements are performed in an indoor realized scenario, including the environmental effects. The experiments show that the proposed AFH combined with ASW algorithms significantly reduce the system latency by 58%.

Pub.: 27 Mar '17, Pinned: 31 Oct '17