Sensor can potentially provide an easy, low-cost alternative to expensive footwear modifications, surgeries, and posture correction accessories

New Delhi: Gait and postural deformities are incapacitating and common in the present world. Studies indicate that the most prominent deformities include splay foot, flat foot, unstable hind foot with protruding heels, high arches, and irregular gait. They are directly associated with poor balance, abnormal posture, swollen knees, and joint weaknesses that cause difficulty in walking.

Therefore, adequate gait and postural deformities monitoring are imperative. They can provide valuable clues to the underlying recovery process or detect various medical conditions, accelerating the patient's recovery and avoiding any long-term harm.

Researchers have been working extensively on postural deformity detection and their efficient corrections. The flexible wearable sensors adhere to the irregularities as mentioned above, wherein the application of specific pressure patterns has a one-to-one association with the type of abnormality.

Researchers at IIT Delhi have developed one such scalable wearable pressure sensor based on a nanocomposite material, that has unique combination of light-sensitive polymer and piezoelectric nanoparticles, which offers the advantage of easy array design for pixelated sensing over large area, simple process flow, and low-cost implementation for human movement monitoring and injury rehabilitation.

A research study titled ‘Machine Learning Assisted Hybrid Transduction Nanocomposite Based Flexible Pressure Sensor Matrix for Human Gait Analysis’ by research scholars Nadeem Tariq Beigh and Faizan Tariq Beigh, and Prof. Dhiman Mallick, all from the Department of Electrical Engineering at IIT Delhi, has  published in Nano Energy (research paper link https://doi.org/10.1016/j.nanoen.2023.108824), which is a leading journal in the field of nanotechnology with impact factor of 17.6. This work is financially supported by I-Hub Foundation for Cobotics, Technology Innovation Hub of IIT Delhi.

The researchers in their study found the reported sensor as fully flexible that can be implemented as a sensor array considering a robust design that comfortably fits inside the insole of varying sizes. It can also be easily attached at the palm or any body part where localized pressure sensing can be useful. The use of dual transduction nanocomposite material in the proposed sensor allows concurrent sensing of mechanical strain as well as contact force/pressure that helps in easy integration with current Machine Learning algorithms by providing higher feature elements.

“The integration of sensors and Machine Learning leads to the invention of intelligent sensors for cutting-edge technologies in fields like healthcare, sports science, defense etc. During the number of tests that we conducted in our laboratory, we found that the proposed sensor can potentially help detect foot problems in adults and children by analyzing the pressure variation on the back end of the foot and converting it into electrical output. Since abnormal hind foot pressure distribution can lead to problems in knee joints, hips, and even spine-related injuries, understanding and correcting it is an important application”, said Dr. Dhiman Mallick, lead researcher and Assistant Professor at Electrical Engineering Department, IIT Delhi.

The sensor generated output is analyzed by conventional Machine Learning models and linked to a person's walking behaviour. By comparing the pressure patterns to those of pre-defined patterns of a normal person, clinical specialists can conclude the type of deformity present.

“The resulting pressure patterns can aid doctors and specialists in designing custom insole that balance out the foot deformity by supporting regions of the foot showing abnormal pressure distribution. In effect, the proposed sensor can potentially provide an easy, low-cost alternative to expensive footwear modifications, surgeries, and posture correction accessories”, Dr. Mallick further said.

Additionally, the sensor can help in understanding different human activities. For instance, it can figure out if the user is walking, running, or doing something else by feeling the pressure changes in user’s hind foot. The sensor considers the variability of foot pressure during various biomechanical movements, which helps it to correlate each pressure pattern to a given activity.

This has tremendous application in smart healthcare systems wherein the activity pattern, exercise intensity, number of steps, etc., form important parameters for critical health analysis in people with diabetes, obesity, etc. Additionally, the sensor can be helpful for elderly fall detection, especially in patients with Parkinson's disorder or who are disabled.

Furthermore, owing to the versatile nature of the developed sensor system, the sensor can be employed in injury rehabilitation. For instance, the sensor has been utilized to assess hand grip strength. This use is crucial when dealing with limb injuries and plays a key role in comprehending recovery. In situations with injuries to the limbs or palms, the strength of the grip is directly related to the healing progress.  

“This is just the beginning but we have already demonstrated the usefulness of the proposed sensor in a number of applications. This shows a step towards an intelligent healthcare evaluation environment”, Dr. Mallick added.

With its application diversity, the developed sensor opens up new horizons for in-house smart devices that overcome the pertinent challenges in the current state-of-the-art sensor technologies. The scope of market penetration of the proposed sensor is immense, and its technological footprint can envelope agriculture, healthcare, the energy sector, industries, sports, etc.

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