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Earth Abundant Manganese Catalysed Sustainable Chemical Transformations
(Indian Institute of Technology, Jodhpur, 2025) Chakraborty, Subrata
The growing interest in Earth-abundant transition metals for organometallic catalysis stems from their economic advantages, availability, and unique catalytic properties. Manganese, the third most abundant transition metal in the Earth's crust, has emerged as a promising alternative to precious metals such as platinum, palladium, and rhodium, which are commonly used in catalytic processes like (de)hydrogenation, hydroboration, hydrosilylation. While precious metal catalysts are renowned for their high activity and robustness, their high cost and limited availability pose significant challenges. In contrast, manganese offers a more sustainable and cost-effective option, though it often requires more advanced catalyst design to match the performance of precious metal-based systems. Manganese catalysts are typically designed around three key principles: metal–ligand bifunctionality, ligand hemi-lability, and redox activity. By optimizing these factors, manganese catalysts can be engineered to achieve competitive turnover numbers, although they may not always match the efficiency of precious metals in certain applications. This thesis provides a comprehensive analysis of the catalytic properties of manganese complexes, comparing their activity, versatility, and efficiency in the direction of alkylation, (de)hydrogenation, deamination and hydration reactions. It also highlights the critical challenges in manganese catalyst design, particularly in ligand optimization, and offers insights into how these catalysts can be improved for broader catalytic applications.
Flexible Organic Transistors with Natural Materials For Eco-friendly Electronics
(Indian Institute of Technology, Jodhpur, 2025-01-08) Tiwari, Shree Parkash
Continuous development of technologies over time has significantly shortened the lifespan of devices, resulting in a substantial increase in electronic waste (E-waste) causing negative impact on environment and ecology. Flexible electronics has emerged as promising technology towards offering solution to this issue by capability of incorporation of nature originated materials in device fabrication through instilling eco-friendliness and potential biodegradability. Organic field-effect transistors (OFET) have been widely investigated as crucial device component for flexible electronics due to its applicability in circuit, sensing, and memory applications. This thesis is an effort to contribute towards flexible biodegradable electronics. Specific emphasis was given on the demonstration of eco-friendly OFETs for circuit and sensing applications with multi-functionality and eventual decomposability, which are essential requirements for smart and sustainable electronics. To start with, various solution processed biocompatible or natural polymers including polyvinylpyrrolidone, silk fibroin, gelatin, chitosan, egg albumen, and cellulose derivative were explored as promising gate dielectrics in OFETs, either as single layer or in bilayer combination with other polymers or a thin high-k hafnium dioxide (HfO2). All these devices were fabricated on indium tin oxide (ITO) coated glass or polyethylene terephthalate (PET) substrate, where ITO acting as bottom electrode. Widely explored pristine TIPS-Pentacene or TIPS-Pentacene: Polystyrene (PS) blend was utilized to form active layer with gold (Au) top electrodes working as source/drain, to demonstrate p-channel transistor characteristics for -5 V operation. Low voltage operation (-3 V) in flexible OFETs was demonstrated using a pristine layer of solution processed gelatin in combination with TIPS-Pentacene: PS blend. These devices exhibited excellent electrical characteristics with extracted field-effect mobility (μ) value approaching to as high as 3.0 cm2 V-1 s-1 with near-zero threshold voltage and low subthreshold swing (SS), along with remarkable operational stability as confirmed by various stability tests including bias-stress, repeatability, cyclic, bending and long-term ambient stability. A very high environmental stability over 24 weeks was observed with almost unchanged electrical characteristics. Circuit applicability of these devices was successfully demonstrated through resistive load inverters. Multifunctionality in OFETs with gelatin/HfO2 hybrid bilayer gate dielectric and TIPS-Pentacene as semiconductor was demonstrated with multi-parameter sensing capabilities for visible/UV light and humidity, which also led to real time breath rate monitoring, a simple tool for wellness monitoring. Maximum field-effect mobility (μmax) of 2 cm2 V-1 s-1 was exhibited with low SS value of ~200 mV/dec., and high current on-off (Ion/Ioff) ratio ~104 for -5 V operation with excellent electrical, operational, and bending stability. For the enhancement of performance and stability in devices with nature originated dielectrics, a composite of gelatin and chitosan was investigated with chitosan acting as a tuning agent to modulate the gate dielectric properties through controlled crosslinking facilitated by the electrostatic interaction and strong hydrogen bonding between the functional groups of polymers. Devices fabricated with a gelatin: chitosan ratio of 10:5 exhibited better electrical stability upon bending for 100 repeated bending cycles compared to other ratios. Circuit applicability, high bias-stress stability, and shelf life for 24 months indicated overall high performance using the composite gate dielectrics. Finally, devices were fabricated on paper substrate thorough process optimization for substrate planarization with polyvinyl alcohol (PVA), silver (Ag) as gate electrode, to move towards eco-sustainable electronics. Cyanoethyl cellulose (CEC), a synthesized version of cellulose was comprehensively investigated as a potential gate dielectric in OFET devices for eco-friendliness. Transistors with CEC dielectric and paper substrate were demonstrated in an effort to produce biodegradable systems for eco-sustainable electronics. These devices exhibited high performance with excellent saturation in the output characteristics for -5 V operation along with remarkable electrical and operational stability. High bendability of devices was confirmed upon application of tensile stress through bending along the channel for the bending radii of 12, 7, and 5-mm. Moreover, high cyclic stability was achieved in devices even after keeping the device in high humid environment with relative humidity reaching to ~100 %. High decomposability in water rich soil in ~20 days was observed due to the microorganisms present in soil environment, confirming excellent biodegradability which is highly essential for eco-sustainable electronics. Due to high performance and biodegradability, these paper-based devices can offer huge potential towards the future flexible and green electronics, and can help in minimizing the impact of E-waste on environment and ecology.
Design and Development of Disposable Microsystems for Sensing Applications
(Indian Institute of Technology, Jodhpur, 0021-09-20) Gupta, Ankur
Sensing and diagnostics have become essential parts for our healthcare monitoring. Disposable microsystems can be potential solution for the same which are designed for single-use while eliminating the risk of cross-contamination between patients. These devices are typically aimed to design for straightforward, one-time use, simplifying the testing process and hence, are of low initial cost. Along with this, it addresses environmental concerns associated with single-use plastics. In this context, Paper-based analytical devices (PADs) are desgined and developed which are economical, recyclable, biocompatible, and robust. They consist of a network of hydrophobic and hydrophilic micro-channels which are capable to handle and quantitatively analyze the target analyte. There is no requirement for the clean-room facility to fabricate such device, and it does not require any external pump for the movement of target analytes. Paper strips have been used for several decades for biomedical assays because they provide a low-cost platform for colorimetric testing. Previously, Müller and Clegg reported the first kind of paper-based microfluidic device in 1949. However, the Whitesides group later explored paper-based microfluidics, and it opened new pathways in this field for the use of paper to develop portable, on-site detection in bio-sensing applications. This research investigates simple fabrication strategies for cost-effective mass manufacturing of disposable microsystems for sensing applications, while utilizing a leak-proof paper-based analytical device (PAD) by creating a hydrophobic zone through the proper penetration of ink into the pores of the paper. An inexpensive disposable colorimetric sensor developed through the assistance of chemometric reaction and tested for the optimization of samples and the determination of glucose for different concentrations (0.5-20 mM and 0.1-0.5 M) with a LOD of 2.92 mML−1. To increase platform's resistance to variations in illumination and camera optics, images taken with several cellphones in various lighting conditions were used to train classifiers, with an accuracy of 72.7%. To enhance the analysis platform’s robustness and make it user-friendly, the image data set was taken at various angles of incident light with an overall accuracy of~ 93%. Further, for the multiplexed detection of the analyte, a unique trident-shaped μPAD has been fabricated on a chemically modified A4 paper, followed by the theoretical and experimental fluid flow. Three different biomarkers, glucose, lactate, and uric acid, were detected through colorimetric enzymatic reaction on the novel trident-shaped disposable PAD, with LOD and coefficient of determination of 0.28 mM, and 0.98, 0.40 mM and 0.97, and 0.22 mM and 0.99) respectively. This platform achieves a high accuracy rate of analyte detection (~ 97%) in predicting three different colorimetric findings, both quantitatively and qualitatively through an Android application. The application's integrated image processing tools autonomously identify the region of interest (ROI) and minimize human error, enhancing the platform’s user-friendliness and precision. Proceeding the work, for the exploration of electrochemical sensing, a non-enzymatic electrochemical sensor was developed for the detection of lactic acid with a sensitivity of 0.00176 mA*μM-1cm-2 and LOD of 0.76 mM, followed by computation studies of reaction molecules.
Next Generation Routing and Data Dissemination Techniques for Vehicular Ad-hoc Networks
(Indian Institute of Technology, Jodhpur, 2024-07-23) Das, Debasis; Das, Sajal K.
Consider a driver on a busy highway where their vehicle immediately receives alerts about a collision occurring three cars ahead, well before it comes into their line of sight. Or imagine a navigation system dynamically rerouting the driver to avoid a newly formed traffic jam just a few kilometers away. This is the capability offered by Vehicular Ad-hoc Networks (VANETs), which enable direct communication between vehicles and roadside infrastructure, establishing a real-time digital network that enhances road safety and optimizes traffic flow. However, deploying VANETs is complex. On actual roads, particularly in developing countries, traffic is highly heterogeneous ranging from cars and buses to motorcycles and auto-rickshaws, all traveling at varying speeds, frequently changing lanes unpredictably, and constantly joining or leaving the network. Traditional communication protocols, originally designed for relatively stable and homogeneous networks, struggle under these conditions: communication links frequently break, message flooding occurs in dense traffic scenarios (known as "broadcast storms"), and critical safety messages that require delivery within 100 milliseconds often fail to meet the stringent latency requirements. This thesis addresses these fundamental networking challenges (packet routing) by developing and validating next-generation routing and data dissemination techniques that maintain reliability despite high node mobility and diverse traffic conditions. Our contributions encompass three different directions: direction-aware forwarding mechanisms,metaheuristic-based clustering frameworks, and hypergraph-based communication models. We first propose three orientation-informed routing protocols, Cosine Similarity-Based Routing (CSBR), Orientation-Based QoS Routing (OBQR), and SDCast leveraging vehicles’movement direction and road context to improve data dissemination. Unlike conventional broadcast or shortest-path schemes, these protocols dynamically bias message forwarding along the direction of traffic flow, reducing redundant transmissions and avoiding relays on vehicles that are likely to move out of range. In CSBR, a cosine similarity metric between vehicle velocity vectors is used to select relay candidates, ensuring that only vehicles with aligned directions participate in rebroadcasting. OBQR builds on this by incorporating multi-constraint QoS metrics (link stability, transit delay, etc.) into routing decisions, using a weighted optimization to find routes that honor safety-critical latency and reliability requirements. Finally, SDCast introduces a hybrid Software-Defined Networking (SDN) architecture into the VANET: a two-tier controller system (a central controller working with local Roadside Units) that orchestrates cluster-based forwarding policies. To improve communication stability and QoS in dynamic conditions, we next develop advanced clustering and routing optimization techniques using metaheuristics. Two frameworks, i.e., MetaLearn and Multi-constraint Routing using Hybrid Metaheuristics (MRMH) are introduced to intelligently organize vehicles into semi-stable clusters and optimize multi-hop routes within and between these clusters. MetaLearn employs a hybrid learning approach: it uses meta-heuristic algorithms (Grey Wolf Optimization (GWO)) to bootstrap efficient clustering, and then applies reinforcement-learning principles (fast adaptation based on prior outcomes) to continually refine routing policies as conditions change. This enables the routing strategy to “learn” from the network’s behavior, quickly adapting to recurring traffic patterns (e.g., rush hour flows) and thereby improving long-term performance. MRMH, on the other hand, hybridizes multiple optimization techniques (GWO and Sequential Quadratic Programming (SQP)) to solve the routing problem under multiple constraints (such as latency, link durability, and bandwidth) simultaneously. By hybridizing metaheuristics methods, MRMH avoids the pitfalls of single-metaheuristic approaches (like premature convergence or high computational cost) and finds high-quality routes that satisfy all QoS requirements even as the network scales. Finally, we present an approach using Spatio-Temporal Information-Aware Hypergraph formulation that generalizes the traditional network graph model to a hypergraph structure. In a hypergraph, an edge (now called a hyperedge) can connect any number of vertices, which in our context means a communication event can directly involve multiple vehicles. This representation is paired with a deep learning-driven routing strategy that uses spatial (geographic/positional) and temporal (time-dependent) dynamics of vehicles and network conditions to make optimized decisions. By capturing higher-order relationships (beyond simple pairwise links) and feeding them into a deep learning algorithm, the network can better anticipate and adapt to changes. Further, we introduce a Software-Defined Fog Computing (SDFC) framework for VANETs,which pushes computational intelligence and control closer to the network edge (the vehicles and roadside units). This enables data processing and decision-making to occur in proximity to where data is generated. By doing so, fog computing can drastically reduce end-to-end communication delays and offload traffic from the core network. In our SDFC framework, VANET management functions (such as cluster formation,routing control, and load balancing) are distributed across a hierarchy of cloud, fog, and edge layers. This design improves scalability and reliability by avoiding single points of failure and by adapting to local conditions. To ensure experimental validations, all proposed techniques were implemented using standard VANET simulation tools and real hardware. Simulations leveraged frameworks like NS-2/NS-3 and OMNeT++ (with the Vehicle in Network Simulations (VEINS) open source library) for network-layer behavior, standard Vehicle-to-Everything (V2X) communication technology (IEEE 802.11p, Cellular-V2X) and Simulation of Urban Mobility (SUMO) for generating realistic vehicle mobility on road layouts imported from OpenStreetMap (openly-licensed data from national mapping agencies and other sources). We seeded simulations with actual city road maps and traffic patterns (including heterogeneous vehicle types, intersections and traffic lights) to closely mirror real-world conditions. Key performance metrics, end-to-end latency, packet delivery ratio, routing overhead, cluster membership time, throughput, and route discovery time were measured across a range of scenarios (urban environments, highways, varying vehicle densities from sparse to congested). Furthermore, the algorithms were tested on a physical testbed: our Duckietown setup (miniature autonomy test bed) and anedge computing platform with Raspberry Pi and JetsonNano devices (working as Onboard Units and Roadside Units) allowed us to verify that the protocols run within real-time constraints on resource-constrained hardware.
Xurography- Based Microfluidic Platform for Mimicking Neuronal cytoarchitecture and Exploring its Application in Neurodegenerative Disease Research
(Indian Institute of Technology, Jodhpur, 2025-01-03) Ghosh, Surajit
The brain is an intricate system composed of millions of neural networks. Deciphering its overall dynamics and the underlying significance of several cues that direct neuronal development, the formation of axons, dendrites, and synapses during wiring and re-wiring remains a formidable challenge in developmental and cellular neuroscience. Although traditional in vitro macroscopic cell culture techniques are easy to perform, they often fail to mimic the complex phenomenon of brain microenvironments. Recent advancements in microfluidic device-based cell culture technologies have successfully overcome the limitations of conventional cell culture methods, enabling the reconstitution of neural cytoarchitecture through precise spatiotemporal regulation of compartmentalized cell culture microenvironments. These lab-on-chip technologies can aid in elucidating the fundamental principles of brain function and provide innovative platforms for screening neurotherapeutics. This thesis offers a succinct overview of the structural and functional aspects of the human nervous system by the reconstitution of the central and peripheral nervous systems on the chip. It highlights the neurological disorders associated with dysfunctions in both systems. It also reviews the several strategies researchers have adopted to mimic neurogenesis on a chip. Additionally, we have designed and developed an economical, innovative microfluidic device utilizing a state-of-the-art Xurography technique. Thereafter, we performed on-chip cell culture studies with primary neurons and SH-SY5Y cells to validate the cytocompatibility of the device. Furthermore, we demonstrated the application of the fabricated device as a coculture model using astrocytes and neurons. The device also served as a drug screening platform for a multi-targeted compound in the differentiated SH-SY5Y cells in the context of Lastly, we also developed a Ferroptosis model that can be linked to neurodegenerative disorders. In this regard, we also investigated the efficacy of a synthesized small molecule inside our fabricated microfluidic device. All these lead to the conclusion that our simple and cost-effective Xurography-based microfluidic device can open gateways to decipher neuronal events inside the human brain and serve as potential platforms for neurodegenerative disease modelling and screening novel therapeutic agents.