Movement is at the core of what makes living beings “alive.” From the movement of our limbs, pumping of the heart and flow of blood to the movement of air in the lungs and microscopic transport of proteins within cells, motion is fundamental to biological systems. Even processes like tissue formation rely on movement. Understanding these mechanisms not only gives us an insight about how living systems function but also paves the way for developing therapies and cures for various diseases.
At the Mechanical Engineering Department of the Indian Institute of Technology Bombay (IIT Bombay), researchers study the mechanics of biological systems through a diverse range of projects, including:
● Mechanics of muscles, tissues and cells
● Rehabilitation, implants and medical devices
● Mechanics of the blood vascular system
● Modeling interactions between the human body and vehicles
Mechanics of muscles, tissues and cells
Mechanics of bones, muscles, ligaments and joints
In the BiOME (Biomechanics, Orthopaedics and Musculoskeletal Engineering) Laboratory, researchers led by Prof Darshan Shah work on musculoskeletal biomechanics. They study the mechanics of bones, muscles, ligaments, tendons and joints using an integrative approach involving in vivo (experiments and measurements directly on the human body), in vitro (physical simulation outside the human body, on artificial, animal or cadaveric specimens) and in silico (computer simulation) research. The integrative approach helps overcome the limitations of the individual methods and makes their research more accurate, fast and cost-effective. Additionally, it paves the way for patient specific insights and tailored treatments.
The team has built knee joint and mandible simulators; and a whole leg simulator that mimics the functionality of the hip, knee and ankle joints along with tendons and muscles of the leg. They develop sensors that can be attached to the human body to track the motion of body segments thereby measuring human movement. These sensors can be deployed not just in the laboratory but also in real life conditions for data collection, enabling more realistic in vivo research. The team experimentally and computationally models musculoskeletal systems.
The team is focussed on studying the joint biomechanics specifically for the Asian population where sitting with folded legs and kneeling are very common contrary to the western countries.
The physiologically relevant knee joint simulator can control and measure forces that the connecting muscles exert on the knee joint in addition to simulating the knee-motion. It is a tool towards translational research as it is a repeatable unit that can provide testing and evaluation of different implant options.
Other physical simulators that the team has developed
● An artificial knee joint model with applications in orthopaedic training
● A mandible (jaw) simulator for testing customised implants of the jaw
● An innovative ankle implant as a solution for people suffering from osteoarthritis
The BiOME lab is working with Indian and international clinicians, physiotherapists and sports therapists to measure and understand different movements of the upper limb and lower limb joints and to explore how joint biomechanics would behave in different healthy and diseased conditions.
The BiOME lab carries out several projects in collaboration with industry and academic partners. They are collaborating with Imperial College London, UK; University of Malaysia, Kuala Lumpur; KU Leuven, Belgium; Sir H.N. Reliance Foundation Hospital, Mumbai and Indian startups such as Digital Darwin and nxtQ.
Prof Darshan Shah has introduced an institute-wide interdisciplinary elective course called 'Joint Biomechanics'. It introduces students to human anatomy and biomechanics from an engineering perspective.
Study and simulation of muscle behaviour
Prof Amit Singh and his team are applying principles of nonlinear solid mechanics to study the contraction of human skeletal muscles. They study muscle operation at all scales, from the cellular to the tissue level.
Using continuum models, they investigate muscle behavior in sarcopenia—the weakening of muscles with age. They examine the active (contraction) and the passive (elastic properties) components of muscle function. A key focus area is to explore how these components are affected by aging and contribute to sarcopenia.
In another project, Prof Amit Singh and his collaborators from other universities are developing analytical and computational models of novel mechanisms that reveal nonlinear interactions between chemical, electrical, and mechanical effects in deformable tissue, particularly cardiac tissue. They are employing the finite element method to model the muscle system that connects the heart to the torso.
Cellular Mechanics
Prof Parag Tandaiya and team model biological matter such as cells, tissues, muscles and other organs to better understand their mechanics and to potentially develop biomedical devices for diagnostics and treatment of various diseases.
Prof Tandaiya’s team studies mechanisms of cellular self-organization and migration. Extracellular matrix is the tissue/material that fills up the space in between the cells. When cells move from one place to another during organ formation, wound healing or cancer progression, the mechanical properties of the extracellular matrix affect the movement of cells. Prof Tandaiya’s team studies how the stress and strain in the extracellular matrix affects the cell movement and the role of stiffness of the extracellular matrix when cells self-align to form tissues.
The team also studies transport of material inside cells. An animal cell is filled with a fluid with small components floating in it. When a component needs to be transported within the cell, nanosized motor proteins called dyneins help move the component from one place to the other. The team studies the different parameters of dyneins.
Mechanics of hearing
A team of researchers in the Acoustics and Hearing Lab at IIT Bombay led by Prof. Sripriya Ramamoorthy is using computational and experimental methods to understand human hearing, improve auditory diagnosis and develop prosthetic devices.
The cochlea and the hair cells inside the ear help us perceive a smaller increase in loudness when the intensity of sound increases by a large amount. Sounds are generated in the cochlea inside the human ear due to nonlinearities in sensory transduction. These sounds undergo complex vibro-acoustic wave-mixing before exiting the cochlea. They are called otoacoustic emissions and can be measured using sensors placed in the ear canal.
While the otoacoustic emissions can be used to diagnose cochlear dysfunction and hearing loss, they contain much more information about the cochlea. These signals, when interpreted properly, could provide information on the specific local region of damage within the cochlea. Targeting this goal, the team in the Acoustics and Hearing Lab measures raw pressure data arising from OAEs and analyse it using a physiology-based computational model of the cochlea along with the outer and middle ear, which predicts the vibro-acoustic wave-mixing phenomena in the cochlea. —----------
Rehabilitation, implants and medical devices
Rehabilitation technologies for movement disorders.
Prof Vivek Sangwan leads his team to develop an automated robotic exoskeleton for rehabilitation of patients with walking disabilities (Adaptive Control of Leg Exoskeletons for Rehabilitation of Stroke and Spinal Cord Injury Patients). The exoskeleton can be especially useful for rehabilitation of stroke patients, where the part of the brain that controls walking may be affected, but the nerve network is intact. Another region in the brain takes over the control and sensing function when walking-associated limb movements are repeated several times daily.
To train a patient to walk manually is tedious and labour intensive and needs at least two or three physiotherapists—one to support the patient and the others to move the patient’s legs to do the walking movements. An exoskeleton helps in supporting the patient and moving their legs. For a non-automated exoskeleton, many patient specific measurements need to be made to adjust the exoskeleton for each patient. The automated robotic exoskeleton that the research team is designing can eliminate the need for manual measurements and adjustments. In addition to supporting and moving the patient, the team’s robotic exoskeleton allows natural movement of the hip and torso (degrees of freedom provided) during walking.
The team is developing algorithms that can self identify some of the patient specific parameters, thus reducing the burden of measurements on the physicians. Their control software estimates the torque and speed needed for the exoskeleton to ‘teach’ the patient to walk. As the patients gradually regain their own neuro-motor control, the machine allows them to move voluntarily.
The team aims to extend the capabilities of the exoskeleton to build an affordable indigenous solution as opposed to similar, prohibitively expensive imported exoskeletons.
Otoscope and ear implant
Prof Sripriya Ramamoorthy and team is developing an Optical coherence tomography otoscope for diagnostics of the middle ear. The conventional and video otoscopes used by ENT doctors provide a view of the eardrum and only a partial view of the middle ear. This view is insufficient for proper diagnosis of the middle ear. Addressing this issue, the team is developing an optical coherence tomography (OCT)-based otoscope combined with tympanometry for diagnostics of the middle ear. OCT is an optical analogue of ultrasound and provides depth information about samples over a few millimetres with micrometer-scale resolution. This technique, combined with low-coherence vibrometry, is used as the basis to develop the OCT otoscope.
The team is also developing hearing aids aiming to reduce occlusion and acoustic feedback
Microfluidic devices for point-of-care diagnostics
Prof Amit Agrawal and his team leverage differences in the physical properties of the components of blood to develop passive microfluidic devices that can efficiently separate blood components.
Blood is not a uniform fluid; it consists of a liquid component, plasma, and cells of different physical properties suspended within it. Separating specific components of blood is crucial for disease diagnosis, especially for conditions where early detection improves survival rates or quality of life. While traditional centrifugation methods are effective, they are time-consuming, labor-intensive, and unsuitable for point-of-care applications.
The team has developed a passive microfluidic device that achieves 100% plasma separation and enables the extraction of platelet-rich plasma (PRP) with approximately 15-fold enrichment, along with platelet-poor plasma. Additionally, their ongoing research on white blood cell (WBC) separation has achieved up to 8-fold enrichment. These microdevices are compact, clog-free, hemolysis-free, and require minimal volume of blood, making them highly suitable for integration into diagnostic systems.
The team has developed a two-fluid numerical model that simulates blood flow in microchannels, to optimize device design and reduce experimental dependency. This model closely aligns with experimental data and accelerates the development of future microdevices. They are now working on a single device that can separate all blood components, including platelets and WBCs, further advancing point-of-care diagnostics.
The team is also testing the blood plasma separator for early stage detection of cancer, in collaboration with ACTREC (The Advanced Centre for Treatment, Research and Education in Cancer), Navi Mumbai.
Development of Medical Devices
Prof B. Ravi leads the Biomedical Engineering and Technology Innovation Centre (BETIC) which builds the necessary ecosystem to develop novel, reliable and affordable medical devices indigenously.
The center provides necessary guidance and support to med-tech innovators, helping them create a product from their concept and hand-holding them through the proof-of-concept and prototype stages. Experts in the field of medicine, mechanics, materials, manufacturing and management help innovators establish their products and market them.
The center has helped develop prosthetics, customised prosthetic design tools, diagnostic devices, surgical tools, wearable devices and rehabilitation tools. BETIC has developed 25 devices, incubated 16 startups, licensed 14 products developed for local industry partners and filed 55 patents.
Mechanics of the blood vascular system
The research group led by Prof Atul Sharma and Prof Janani Srree Muralidharan specialises in modeling blood flow through the human circulatory systems in healthy and diseased conditions. They use computational models to study the dynamics of blood flow across multiple length scales (different sized blood vessels, from narrowest to the widest).
The team investigates how phenomena at smaller scales impact larger-scale disease progression. They first simulate the blood flow dynamics, and then analyse how various parameters influence the underlying physics of the problem. Through the multi-scale modelling they aim to detect diseased arteries and identify potential interventions that could either prevent the progression of the disease or offer effective treatments. Their current research focuses on the micro-vessel scale.
Blood-pressure induced tissue deformation and haemodynamics-induced acoustics The team led by Prof Atul Sharma and Prof Janani Srree Muralidharan have developed computational methods to study the biomechanics of blood flow (hemodynamics), tissue deformation due to blood pressure, and sound generation caused by blood flow (murmurs). Their key innovations include improved dynamic meshing, a finite volume method for structural modelling, a low Mach approximation-based numerical model for acoustics, and a unification of planar and axisymmetric frameworks for complex geometry problems. They have created an in-house computational tool for simulating the interactions between blood flow, tissue structure, and acoustics (Computational Fluid Structure Acoustic Interaction) (CFSAI).
The team has shown that a pressure-rate parameter can reliably identify the acoustic signals associated with murmurs, offering a better understanding of what causes murmurs and opening new possibilities for phonoangiography. By integrating tissue flexibility and advanced computational models into diagnostics, the team, for the first time, demonstrated that ignoring tissue deformation overestimates stenosis severity, highlighting the need for flexible-tissue models.
The team has proposed a semi-analytical, computationally efficient approach called Fluid flexible-Structure Acoustics Interaction (FfSAI), which is practical for point-of-care applications.
The team uses the CFSAI tool to train a machine learning (ML) model to classify disease severity, leading to the potential for a digital stethoscope-based system to assess conditions like arterial stenosis and aneurysms in real time. They have developed a new technique to detect cardiovascular diseases (CVDs) early using phonoangiography.
In another project, Prof Janani Srree Murallidharan and team computationally model how blood clots form and grow in blood vessels and how blood moves around such clots. The team assesses the risk of the blood clots breaking off and blocking smaller blood vessels. These simulations help identify risk factors for a stroke and improve treatment strategies for stroke patients.
Magnetically Driven Targeted Drug Delivery (TDD) and Bubble Dynamics
Prof Janani Srree Murallidharan and team are developing computational techniques to simulate the effect of using external magnetic fields to control and direct drug carriers such as nanoparticles or bubbles to specific sites of injury or disease within the body. The method allows for precise and localised drug delivery, and reduces the side effects of broad spectrum drugs. The method can be highly effective for delivering drugs at a higher concentration, especially for cancer and neurological disorders.
The team is currently modelling a single drop of the drug moving through medium sized blood vessels and computing the various forces acting on it assuming the blood vessels to be simple rigid pipes. They plan to refine the model for different sized blood vessels, multiple drops and incorporate other complexities such as non-newtonian effects.
The computational methodology developed to model drops moving inside blood vessels can also be used to study other associated problems such as modelling air emboli dynamics in blood vessels. The team studies how air bubbles traverse the vascular network, how they get trapped and how they dissolve. Understanding the dissolution and dynamics of air bubbles will prove critical in helping patients who have emboli receive timely medical care.
Aneurysm Risk Prediction
Prof Shiva Gopalakrishnan and team apply CFD (Computational Fluid Dynamics) techniques for aneurysm risk prediction.
Aneurysms are abnormal bulges in arteries caused by weakened vessel walls, posing a rupture risk. Though the rupture rate is low, those in the brain, heart, and abdomen can be life-threatening. Often detected incidentally during unrelated scans, aneurysms can be treated surgically or via endovascular methods, though these carry risks. Accurately assessing rupture risk remains a key challenge.
Rupture risk depends on factors such as aneurysm size, location, growth rate, smoking habit, and age. These factors are currently used to decide the rupture risk and to train machine learning models to identify rupture risk. However, no currently available clinical tool reliably predicts patient-specific risk. Blood flow patterns (hemodynamics), studied through computational fluid dynamics (CFD), strongly correlate with rupture risk.
While parameters like wall shear stress and turbulence show promise, no single measure is predictive, and CFD isn’t yet clinically viable.
The team aims to predict aneurysm rupture risk using a database of aneurysm anatomies with known outcomes. Their approach integrates CFD analysis with AI to optimize hemodynamic predictors.
Modeling interactions between the human body and vehicles.
Prof P. Seshu and team study automobile-human interaction with a view to improve comfort when travelling in automobiles. People using road transport experience vibrations while traveling in automobiles.
Extended exposure to vibrations in moving vehicles can be uncomfortable and sometimes even harmful. For passengers and drivers, especially traveling long distances in buses, an ergonomically designed seat can make their ride more comfortable.
The researchers at the Mechanical Engineering Department computationally model the human-vehicle system. They use the model to evaluate forces acting on the human body and study the effect of vertical and horizontal vibrations. They have developed models with many degrees of freedom. By minimising the error between numerical simulations and experimental results available in literature, they have derived some of the parameters of the computational/virtual models of humans.The only parameter that passengers can control is the back rest angle, that too, when the seats have adjustable back rests. The model helps evaluate the best back rest angle for passenger comfort.
The researchers are further simulating the automobile-human system specifically for the driver. Apart from the vibrations from the seat similar to passengers, the driver experiences vibrations from the steering wheel and the pedals. The research team aims to develop interventions to protect the driver from the ill effects of extended exposure to vehicle vibrations and to make driving more comfortable.
The team has integrated the passenger seat model in the full vehicle model. They also study the effect of random road variations and road bumps on the human vehicle system. These results and the modelling methodology can help better analyse biodynamic response of the passenger and driver.