Smart saddle rides ahead
A wireless sensing system that uses a triboelectric nanogenerator (TENG) aims to help equestrians improve their biomechanics and alert others when a rider takes a fall.
Researchers from the University of Chinese Academy of Sciences and the Georgia Institute of Technology, USA, have made a thin, flexible, disk-shaped TENG that flattens when depressed, transferring electrons from one electrode to another and generating a current. It rebounds when pressure is removed, stopping the current flow.
The paper, Self-rebound cambered triboelectric nanogenerator array for self-powered sensing in kinematic analytics, published in ACS Nano, describes how an array of seven self-rebound cambered triboelectric nanogenerators (SRT-TENG) are assembled on the saddle’s surface to distinguish differences in pressure in various regions of the seat.
The paper reads, ‘A cambered rubber cover made of thermoplastic polyurethane (TPU) with 40mm diameter acts as the top layer, having good mechanical properties and excellent flexibility. A copper electrode layer is attached to it, a fluorinated ethylene propylene (FEP, thickness of 80μm) thin film was employed as the top triboelectric layer and stuck on the copper electrode, which has strong tendency to gain electrons.
‘The substrate was fabricated of a thin acrylic plate…made with a laser cutter and integrated tightly with the cambered cover, so that it can well adapt to different equipment because of the adaptable rigidity. An aluminium film was attached to the acrylic substrate and was used both as another triboelectric layer and as an electrode.’
By collecting and analysing different voltages at the seven points, the distribution of pressure can be calculated and information gathered about the riding pitch.
‘The smart saddle also detected when a person was standing up and sitting down. When a rider falls off, the system can transmit a wireless signal to alert others, a safety feature that could allow an injured rider to be quickly found and treated, which is especially important when riding alone,’ explains Professor Baodong Chen from the University in China.
The electric output and performance has been tested with a programmable electrometer, with a vertical linear motor applied to drive the SRC-TENG with different parameters. Results show the smart saddle has a response time of 16ms.
Chen says, ‘The next step [will be] to improve sensing and monitoring by optimising the structural and kinematic analysis system.’