Motion Tracking with Smart Garments and Textile-Based Electronics

Significance 

Smart garments, a subset of wearable devices, offer a unique advantage due to their natural contact with the body and ability to conform to its shape. Unlike traditional wearables like smartwatches or fitness trackers, smart garments can simultaneously sense motion at various locations on the body, making them an attractive choice for unobtrusive, comprehensive motion tracking. Additionally, smart garments have the potential to eliminate the need for bulky power sources, rigid components, and wired connections, making them more user-friendly and comfortable for daily use.

Recent efforts in smart garment development have mainly focused on two categories of wireless sensing platforms. The first category utilizes common wireless communication protocols (e.g., Bluetooth, NFC, RFID) with commercially available sensor tags. While functional, these systems often involve rigid components and require physical connections with microcontrollers or power sources. The second category, which is the focus of this study, employs inductive coupling with inductor-capacitor (LC) circuits as sensors. LC circuits, consisting of only two components, inductors (L) and capacitors (C), are highly suitable for textile-based sensors due to their simplicity and ease of integration into textiles.

Indeed, the field of mobile health (mHealth) has made remarkable strides in recent years, offering personalized and remote healthcare monitoring solutions. The increasing miniaturization of mHealth technologies, including portable, implantable, and wearable devices, has opened up new possibilities for monitoring various physiological parameters to enhance wellness. Among the many aspects of human health, tracking motion and biomechanical movements have gained considerable attention due to their relevance in rehabilitation, prosthesis control, gait analysis, and long-term physiological signal monitoring. While several wearable technologies exist for this purpose, the integration of sensors into clothing, known as smart garments, holds significant promise for unobtrusive and comfortable motion tracking.

To this account, a new study published in the Journal Advanced Science by a team of Swiss scientists led by Professor Carlo Menon at ETH Zürich. The study introduces a novel approach to motion tracking through the development of a smart garment integrated with textile-based electronics. This technology represents a remarkable advancement in the field of wearable sensors, with profound implications for healthcare, rehabilitation, and athletic performance monitoring.

The study conducted by Professor Menon’s team explores the potential of LC circuits as textile-based sensors for motion tracking. The LC sensors, composed of a textile inductor and a textile capacitor, respond to strain through changes in capacitance, resulting in a shift in the resonance frequency of the LC circuit. This shift can be wirelessly detected through inductive coupling, making it possible to monitor motion in real-time.

One of the key advantages of textile-based LC sensors is their flexibility and stretchability, making them suitable for tracking medium to fast-paced movements such as walking, running, or climbing stairs. These sensors exhibit a linear response to strain, ensuring accurate and reliable motion tracking. Furthermore, they demonstrate excellent long-term stability, which is crucial for wearable devices intended for continuous use.

While the concept of textile-based LC sensors for motion tracking is revolutionary, the technology requires a compatible reader to wirelessly retrieve and interpret the sensor’s data. Traditional readers like vector network analyzers (VNAs) are bulky, expensive, and impractical for daily use. To address this challenge, Professor Menon’s team designed a lightweight and low-cost reader called the fReader.

The fReader is a compact device that can comfortably fit in the pocket of a smart garment. It operates by inductively coupling with the textile inductor in the garment, allowing it to detect changes in the capacitance of the textile capacitor in response to motion. The fReader then wirelessly communicates with a smartphone application, providing real-time data on motion-related parameters.

The fReader offers several advantages over traditional VNAs. It provides faster data acquisition with higher sampling rates, making it suitable for tracking natural-paced human motion. Moreover, it can operate using the power supplied by the smartphone itself, enhancing its practicality and user-friendliness. The simplicity of the fReader’s circuit design, utilizing readily available components, also opens up the possibility of integrating it directly into smartphone hardware in the future.

The development of smart garments with textile-based LC sensors and the fReader has significant implications for various fields, including healthcare, rehabilitation, athletic performance improvement, and injury prevention. Here are some notable applications:

-Rehabilitation: Smart garments equipped with textile-based LC sensors can play a crucial role in rehabilitation programs. They enable real-time monitoring of patients’ movements and joint angles, allowing healthcare professionals to track progress and make informed decisions about treatment plans. -Prosthesis Control: Individuals with prosthetic limbs can benefit from smart garments that provide precise motion tracking. This technology can improve the control and functionality of prosthetic devices, enhancing the quality of life for amputees.

-Gait Analysis: Gait analysis is essential for diagnosing and managing various musculoskeletal and neurological conditions. Smart garments can offer a non-invasive and convenient way to collect data on gait patterns, helping researchers and clinicians make informed assessments.

-Athletic Performance Monitoring: Athletes and sports enthusiasts can use smart garments to monitor their movements during training and competition. This data can inform training strategies, prevent injuries, and optimize performance.

-Wellness and Lifestyle: Beyond clinical applications, smart garments can be used to promote general wellness by encouraging physical activity and tracking calorie expenditure. These garments provide individuals with valuable insights into their daily movements and activity levels.

The study conducted by Professor Carlo Menon’s team at ETH Zürich represents an important leap forward in the field of wearable technology. By combining textile-based LC sensors with the innovative fReader, they have created a comprehensive solution for motion tracking in a comfortable and unobtrusive form. This technology has the potential to revolutionize healthcare, rehabilitation, and athletic performance monitoring, offering new opportunities for personalized, remote monitoring and improving the quality of life for countless individuals.

Motion Tracking with Smart Garments and Textile-Based Electronics - Advances in Engineering
Passive-wireless sensing system for motion-tracking with smart garment. Image credit: Journal Advanced Science, 2023

About the author

Prof. Dr. Carlo Menon

ETH Zürich
Dep. of Health Sciences and Technology

Prof. Menon’s laboratory, the BIOMEDICAL AND MOBILE HEALTH TECHNOLOGY LAB, focuses primarily on wearable technology. This includes novel materials and sensors for electronic textiles (e-​textiles) or other wearables, as well as innovative computational methods for processing bio-​signals and monitoring biomarkers detected by our sensing technology. We aim to assist individuals to live healthier lives or to recover from neuromuscular/neurological conditions. We are designing the next generation of wearables for sports and personalized medicine.

Reference

Galli V, Sailapu SK, Cuthbert TJ, Ahmadizadeh C, Hannigan BC, Menon C. Passive and Wireless All-Textile Wearable Sensor System. Adv Sci (Weinh). 2023 ;10(22):e2206665. doi: 10.1002/advs.202206665.

Go to Adv Sci (Weinh).

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