Department of Engineering Design

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

The introduction of foreign cargo into living cells with high delivery efficiency and cell viability is a challenge in cell biology and biomedical research. Here, we demonstrate a nanosecond pulse laser-activated photoporation for highly efficient intracellular delivery using titanium dioxide (TiO2) microspikes as a substratum. The TiO2microspikes were formed on titanium (Ti) substrate using an electrochemical anodization process. Cells were cultured on top of the TiO2microspikes as a monolayer, and the biomolecule was added. Due to pulse laser exposure of the TiO2microspike-cell membrane interface, the microspikes heat up and induce cavitation bubbles, which rapidly grow, coalesce and collapse to induce explosion, resulting in very strong fluid flow at the cell membrane surface. Thus, the cell plasma membrane disrupts and creates transient nanopores, allowing delivery of biomolecules into cells by a simple diffusion process. By this technique, we successfully delivered propidium iodide (PI) dye in HeLa cells with high delivery efficiency (93%) and high cell viability (98%) using 7 mJ pulse energy at 650 nm wavelength. Thus, our TiO2microspike-based platform is compact, easy to use, and potentially applicable for therapeutic and diagnostic purposes. © The Royal Society of Chemistry 2021.

World University root node

Department of Mechanical Engineering

Fulltext

RSC Advances

Fabrication of TiO2microspikes for highly efficient intracellular delivery by pulse laser-assisted photoporation

Cells exert, sense, and respond to the different physical forces through diverse mechanisms and translating them into biochemical signals. The adhesion of cells is crucial in various developmental functions, such as to maintain tissue morphogenesis and homeostasis and activate critical signaling pathways regulating survival, migration, gene expression, and differentiation. More importantly, any mutations of adhesion receptors can lead to developmental disorders and diseases. Thus, it is essential to understand the regulation of cell adhesion during development and its contribution to various conditions with the help of quantitative methods. The techniques involved in offering different functionalities such as surface imaging to detect forces present at the cell-matrix and deliver quantitative parameters will help characterize the changes for various diseases. Here, we have briefly reviewed single-cell mechanical properties for mechanotransduction studies using standard and recently developed techniques. This is used to functionalize from the measurement of cellular deformability to the quantification of the interaction forces generated by a cell and exerted on its surroundings at single-cell with attachment and detachment events. The adhesive force measurement for single-cell microorganisms and single-molecules is emphasized as well. This focused review should be useful in laying out experiments which would bring the method to a broader range of research in the future.

Cells

A Review of Single-Cell Adhesion Force Kinetics and Applications

The demand for light-weight materials, exhibiting superior strength and higher toughness, has increased attention to cryogenic temperature rolling as it produces bi-modal microstructures with improved mechanical properties. The samples were cryorolled to a final thickness of 1 mm after thickness reductions of 50%, 66.66%, 75%, and 80%. The ballistic behavior of cryorolled AA 6082 aluminum alloy with different rolling strains/thickness reductions was investigated in this study. The cryorolled Al alloys were subjected to normal high-speed impact using dome-shaped projectiles at velocities between 50 and 250 m/s. The 66.66% thickness reduced samples exhibited higher impact resistance, especially at higher impact velocities. The maximum energy absorption of 106.43 J was observed for 66.66% thickness reduced sample at an impact velocity of 234.38 m/s. This study suggests the existence of an optimal value of cryogenic rolling strain for superior impact resistance, possibly due to an ideal combination of coarse and fine grains in the resulting bimodal microstructure. © 2021, ASM International.

Department of Aerospace Engineering

Journal of Materials Engineering and Performance

Effect of Different Cryogenic Rolling Strains on the Impact Properties of 6082 Aluminum Alloy

Dynamic prediction of queues and delays at signalized intersections utilize data obtained from automated traffic sensors as inputs for Intelligent Transportation Systems (ITS) applications. Errors are inevitable during automated data handling, especially when the traffic involved is heterogeneous and lacking in lane discipline. This paper presents a model-based estimation scheme that can handle both mixed traffic conditions and erroneous detector input data to estimate queue and, in turn, delay. The models were developed for Queue within Advance Detector (QWAD) and Queue beyond Advance Detector (QBAD) scenario. The statistical properties of detector errors were incorporated into the estimation scheme, and the scheme was tested for varying traffic conditions. The estimation scheme’s performance was evaluated using field data from a signalized intersection in Chennai, India, and simulated data. It is found that the incorporation of statistical properties of detector error allows accurate estimation of queues and delays despite erroneous data input. © 2021 Informa UK Limited, trading as Taylor &amp; Francis Group.

Department Of Civil Engineering

Transportation Letters

Dynamical systems approach for queue and delay estimation at signalized intersections under mixed traffic conditions

BACKGROUND AND OBJECTIVE: This article describes a fully automatic system for classifying various spinal degenerative phenotypes namely Modic changes, endplate defects and focal changes which are associated with lower back pain. These are obtained from T1/T2 Magnetic Resonance Imaging (MRI) scans. Lower back pain is a predominantly occurring ailment, which is prone to have various roots including the anatomical and pathophysciological aspects. Clinicians and radiologist use MRI to assess and evaluate the extent of damage, cause, and to decide on the future course of treatment. In large healthcare systems, to circumvent the manual reading of various image slices, we describe a system to automate the classification of various vertebral degeneracies that cause lower back pain. METHODS: We implement a combination of feature extraction, image analysis based on geometry and classification using machine learning techniques for identifying vertebral degeneracies. Image features like local binary pattern, Hu's moments and gray level co-occurrence matrix (GLCM) based features are extracted to identify Modic changes, endplate defects, and presence of any focal changes. A combination of feature set is used for describing the extent of Modic change on the end plate. Feature sensitivity studies towards efficient classification is presented. A STIR based acute/chronic classification is also attempted in the current work. RESULTS: The implemented method is tested and validated over a dataset containing 100 patients. The proposed framework for detecting the extent of Modic change achieves an accuracy of 85.91%. From the feature sensitivity analysis, it is revealed that entropy based measure obtained from gray level co-occurrence matrix alone is sufficient for detection of focal changes. The classification performance for detecting endplate defect is highly sensitive to the first 2 Hu's moments. CONCLUSION: A novel approach to identify the allied vertebral degenerations and extent of Modic changes in vertebrae by exploiting image features and classification through machine learning is proposed. This shall assist radiologists in detecting abnormalities and in treatment planning. © 2021 IOP Publishing Ltd.

Biomedical physics & engineering express

Classification of certain vertebral degenerations using MRI image features

In this paper, we propose a Delaunay triangulation based algorithmic framework for the 2D point set type discernment and its reconstruction. The point set discernment deals with determining whether the given point set S consists of only the points sampled along the boundary of an object (referred to as boundary sample) or S is distributed across the object (referred to as dot-pattern). In general, the existing approaches deal with the reconstruction of an a priori known input type - boundary sample or dot-pattern. Our approach works on both sets of input data type by first identifying the input type that a given point set belongs to. To distinguish the point set type, we introduce the notion of Petal-Ratio(PR) which captures the ratio of the longest edge to the smallest edge emanating from a vertex in Delaunay triangulation. Further, we employ the Petal-Ratio as the essence to design simple reconstruction algorithms pertaining to each input type that unveil the shape of the object hidden in the given point set. The reconstruction algorithms start with computing the Delaunay triangulation of the given point set and for each vertex, the Petal-Ratio is calculated. Following this, the edges are removed based on the value of the PR for every vertex to arrive at the boundaries. Theoretical analysis of determining appropriate values of PRs under ϵ- sampling and minimal reach sampling models have been presented. Unlike many other algorithms, our approach is non-parametric and non-feature specific that can capture features like disconnected components, multiple holes even with the presence of outliers, self-intersection (only for boundary sample) and open curves (only for boundary sample). Moreover, our algorithms take only one pass to reconstruct the hole boundaries as well as outer boundary irrespective of the object features like the number of holes and the number of components. The comparative analysis shows that our algorithms perform equally well or better than their counterparts for the objects with contrasting features. We also demonstrate that the proposed idea can be easily extended to surface reconstruction. © 2020 Elsevier B.V.

Computer Aided Geometric Design

A sampling type discernment approach towards reconstruction of a point set in R2

The present work investigates impact behaviour of additively manufactured AlSi10Mg alloy and ballistic limit of projectiles using FEM simulations. Tensile tests, dynamic tests and elevated temperature tensile tests simulations were performed on smooth and notched specimens to calculate Johnson–Cook material and damage model parameters, which are subsequenty given as inputs for impact simulation. The relationship between residual velocity versus initial projectile velocity is expressed using Jonas–Lambert’s model for calculating ballistic limit. The effects of projectile velocity, its shape, thickness and material property of AlSi10Mg on ballistic limit were thoroughly investigated. C3D8R elements are used to discretize the target plate and mesh transition zone was created in impact region. Johnson–Cook elasto-viscoplastic model was employed to study the ballistic resistance behaviour of AlSi10Mg alloy. Fracture energy value of 43.6 kN/m for AlSi10Mg alloy is used to initiate the damage in target plate. All FE simulations were performed by using ABAQUS/Explicit. It is observed that ballistic impact on 3D printed AlSi10Mg has shown plugging and petaling failure when hemispherical projectile was used while plugging failure in the case of blunt projectiles. The ballistic limit of hemispherical projectiles is found to be higher (311 m/s, 400 m/s) compared to the blunt projectiles (216.5 m/s, 245 m/s). The impact velocity to completely penerate 6 mm thick target plate is relatively higher as compared to 3 mm thick target plate for both projectiles. © 2021, Society for Experimental Mechanics, Inc.

Department of Applied Mechanics

Department Of Physics

Journal of Dynamic Behavior of Materials

FEM Simulation of High Speed Impact Behaviour of Additively Manufactured AlSi10Mg Alloy

A blended FC-V-50 and TZ-001 polymer-based microdisk laser was fabricated by the ink-jet printing method and used for biosensing applications. The FC-V-50 polymer has a negative charge due to the presence of carboxyl functional groups, and the TZ-001 polymer has a positive charge due to the tertiary amine group at a pH of seven. In biosensing applications, non-specific adsorption due to opposite charges of biomolecules and microdisk surfaces can adversely affect the performance of the biosensor. By mixing FC-V-50 and TZ-001 polymers in different ratios, the microdisk surface charge was controlled, and the non-specific adsorption of bovine serum albumin and lysozyme was studied. In addition, the label-free biosensing of streptavidin was demonstrated using a blended polymer-based microdisk laser. This work reports, to the best of our knowledge, the first demonstration of a blended polymer microdisk laser for controlling the non-specific adsorption of biomolecules. © 2021 Optical Society of America

Optics Letters

Ink-jet printed, blended polymer-based microdisk resonators for controlling non-specific adsorption of biomolecules

The morphology of fine microstructure arising from reversible martensitic transformations is known to depend on the sample size and orientation to applied thermal or mechanical loading. In this paper we study these effects using a novel discrete particle approach. Our new approach uses a multibody interparticle interaction for the discrete particles which is obtained directly from a polyconvex continuum free energy appropriate for such materials. In order to study the interfaces between the austenite and martensite phases, the material is subjected to a temperature gradient. A competition between self-accommodation which causes formation of twinned martensite and the requirement of compatibility of the phases on the interfaces results in very distinctive microstructures. We study the effect of the angle between the applied temperature gradient and the orientation of the parent phase on the phase boundary. In smaller samples, a phase boundary between austenite and a single variant of martensite forms due to the effect of the free surface and the resultant microstructure takes a banded form. Detwinning under applied mechanical loading is strongly dependent on the initial microstructure. The implicit kinetic relation for twin boundary propagation of this approach shows a classical stick-slip form. © 2020

Acta Materialia

Modeling size and orientation effects on the morphology of microstructure formed in martensitic phase transformations using a novel discrete particle model

Frugal innovations or frugal products are catching up technologically to serve the needs of humankind. Their features including minimal material consumption, affordability and good functionality make them green from the point of view of sustainable development. However, their no-frills structure typically also necessitates application of rigorous procedures for their design. This chapter stresses on the need for stringent quality control after creating a frugal product out of the rigorous frugal-design process. The quality checks would aid in developing long-term competitive solutions for frugal products while the control would facilitate adherence to stringent product specifications. Accordingly, this chapter stresses the breaking up of quality check into two parts for confirming both the rigor of design procedures and also performance of resulting frugal products. © 2021, Springer Nature Switzerland AG.