Portable human-machine interface (HMI) devices can be used to control machines, computers, music devices, and other systems. However, conventional HMIs deal with the presence of sweat on human skin.
A team of scientists managed to overcome this obstacle. Its development can be seen in the attached images. The left panel shows an array of magnetoelastic sensors, which adapts to human skin and can function even when exposed to liquids. It is able to interact with the control components of a music speaker: play, pause, next and previous. On the right, you can see that the magnetoelastic sensor array, which by the way runs on its own power, is rollable and stretchable.
Expanding the possibilities of using human-machine interfaces
In research published in Applied Physics Reviews, a team of scientists from the University of California at Los Angeles, United States (UCLA), describe the development of a type of interface that is extensible, inexpensive and waterproof. This device is based on an array of soft magnetoelastic sensors, capable of transforming the mechanical pressure of a finger press into an electrical signal.
The device consists of two main components. The first component is a layer that translates mechanical movement into a magnetic response. It consists of a set of micromagnets in a porous silicone matrix that can convert the gentle pressure of the fingertip into a variation of the magnetic field. Thanks to this, no batteries or other external power components are required, since all the power required comes from the movements of its user, which makes this alternative more ecological and sustainable.
The second component is a magnetic induction layer consisting of stamped liquid metal coils. These coils respond to changes in the magnetic field and generate electricity through the phenomenon of electromagnetic induction.
“Due to the flexibility and durability of the material, the magnetoelastic sensor array can generate stable energy under deformations, such as rolling, bending, and stretching”said the project’s lead author, Jun Chen, a researcher at UCLA. “Because of these compelling features, the device can be adopted for HMI powered by the human body by transforming human biomechanical activities into electrical signals”he added.
During the process of investigating possible techniques for manufacturing, assembling, and optimizing the device, the researchers discovered that they could strike a balance between performance and flexibility by controlling the thickness of the flexible film and the concentration of the magnetic particles.
The device was tested in a variety of real-world situations, including in the presence of a spray of water, equivalent to that of a shower, a storm, or during vigorous athletic activity. The device worked well when wet, since according to the analyzes carried out, the device’s magnetic field was not greatly affected by the presence of water.
To test their system, the researchers conducted a series of experiments in which a subject applied finger taps to turn a lamp on and off and control a music player.
“Our magnetoelastic sensor array not only works wirelessly like the on/off buttons on a lamp, but also controls the command functions of a music player, representing play, pause, next and previous actions”Chen said.
The sophistication and complexity that can be seen in solutions arising from research projects in this category can be interpreted as an indicator of the direction that the technology in question is taking. In this case, the devices wearables they could be favored with a greater versatility of use, in case of adopting this remote control mechanism.
