To control computers, machines, music players, and other such systems, wearable human-machine interface devices or HMIs can be used. The presence of sweat on human skin is a challenge for traditional HMIs.
(Left) Photo of the magnetoelastic sensor array, which conforms to human skin and can function even when exposed to liquid. It can interact with a music speaker’s command components: play, pause, next, and previous. (Right two) The self-powered magnetoelastic sensor array is rollable and stretchable. Image credit: The Jun Chen Research Group at UCLA.
Researchers at UCLA explain their development of an HMI type that is inexpensive, stretchable, and waterproof in Applied Physics Review by AIP Publishing. The device is founded on a soft magnetoelastic sensor array that transforms mechanical pressure into an electrical signal from the press of a finger.
Two main components are involved in the device. A layer translating mechanical motion into a magnetic response is the first component. It comprises a set of micromagnets in a porous silicone matrix that can transform the mild fingertip pressure into a magnetic field difference.
A magnetic induction layer comprising patterned liquid metal coils is the second component. These coils react to the magnetic field variations and create electricity via the electromagnetic induction phenomenon.
Owing to the material’s flexibility and durability, the magnetoelastic sensor array can generate stable power under deformations, such as rolling, folding, and stretching. Due to these compelling features, the device can be adopted for human-body powered HMI by transforming human biomechanical activities into electrical signals.
Jun Chen, Study Author, University of California, Los Angeles
The motion of the wearer offers the power needed for the HMI to function. This implies that no batteries or other external power supplies are needed, which renders the HMI more sustainable and eco-friendly.
The device was tested in a diverse array of real-time scenarios, including in the presence of a water spray, for example, it might be present in the shower, a rainstorm, or during extreme athletic activity. It functioned well while it was wet because the magnetic field was not really impacted by the existence of water.
To balance the biomechanical-to-electrical energy conversion of the device, the researchers examined an array of assembly and fabrication techniques. They discovered that they can gain stability between performance and flexibility by controlling the flexible film’s thickness and the magnetic particles’ concentration.
The investigators performed a variety of experiments to test their system, in which a subject applied taps of fingers to switch a lamp on or off and control a music player.
Our magnetoelastic sensor array not only wirelessly functions as the on and off buttons of a lamp but also controls a music player’s command features, representing the actions of play, pause, next, and previous.
Jun Chen, Study Author, University of California, Los Angeles
These assessments show new promise for versatile water-resistant HMIs that could be used to control several kinds of smart devices.
Journal Reference:
Xu, J., et al (2022). A programmable magnetoelastic sensor array for self-powered human-machine interface. Applied Physics Review. doi.org/10.1063/5.0094289.