Researchers develop flexible, low cost sensors that can be sewn directly into athletic clothing

At the upper echelons of many sports, athlete performance is continuously monitored during training. Compact sensor arrays, typically worn under clothing, collect data on body position, acceleration, and a range of other forces and motions experienced by the athlete, all with the aim of improving their overall performance. Sometimes, wearable technologies play a more direct role in sport – a lightweight vest, with metres of embedded piezoelectric cables, have been worn by Taekwondo competitors since the 2012 Olympic Games. Similarly instrumented helmets and socks are also required, and together these devices measure the strength and position of strikes on the athlete, which is used to score their performance.  

But researchers from the Intelligent Wearable Engineering Research Center at Qingdao University have taken that a step further – they’ve developed textile-based sensors that can be sewn into the fabric of an athlete’s clothing. They report on this work in a recent issue of in Nano Energy [DOI: 10.1016/j.nanoen.2021.105941], and their E-textile combines different architectures within the same sensor, allowing it to monitor strain and pressure simultaneously.

To ensure that the fabric can be worn comfortably while accurately responding to motion, they started with a core-sheath yarn structure very commonly used in elastic textiles. For the sheath material, they fabricated a conductive rGO/CNT fibre, which they then coated with a microlayer of insulating polyurethane (PU). The fibres were then twisted around a polyacrylonitrile (PAN) core, producing a conductive yarn that changes its resistance predictably in response to stretching. It also displayed good durability, with samples of the yarn retaining 98 % of its resistivity after 100,000 strain cycles.

This yarn was then woven through pieces of knitted fabric (measuring 1 cm x 1 cm) made from silver fibres. A spacer layer was placed between and bonded to two layers of this electrode textile – this formed a fabric-based capacitive sensor that changes its electrical response with applied pressure. It displayed good sensitivity over a wide detection range, including pressures typical of a heavy strike in taekwondo.

To produce the final E-textile, a 5 × 5 array of these capacitive sensors was then sandwiched between two pieces of stretchy, breathable knitted fabric made from spandex and cotton yarns. The E-textile could then be incorporated into key positions on a taekwondo training suit – namely at the knee and on the chest – to detect stretching and pressure deformation in real-time. In both cases, the E-textile was shown to reliably monitor the tension and pressure forces experienced by a taekwondo athlete. The textile was also suitably breathable, with air and vapour values comparable to those of other training fabrics. The authors say that their “fabric-based sensing technology allows for precise monitoring of athletic movement and form, illustrating its potential application in Taekwondo and robust physical training analysis.”


Yulong Ma, Jingyu Ouyang, Tahir Raza, Pan Li, Aijia Jian, Zengqing Li, Hong Liu, Min Chen, Xueji Zhang, Lijun Qu, Mingwei Tian, Guangming Tao. “Flexible all-textile dual tactile-tension sensors for monitoring athletic motion during taekwondo”, Nano Energy 85 (2021) 105941. DOI: 10.1016/j.nanoen.2021.105941