Successfully fabricated transparent, flexible speaker from gel ion

A team of researchers from Harvard University's School of Engineering and Applied Sciences (SEAS) has created a flexible speaker from gel ion material. The speaker is almost transparent if viewed with the naked eye and can produce high quality sound in the audible sound spectrum of the ear. Through this invention, they demonstrated the idea that electronic devices can transmit electrical signals in a way similar to the human nervous system.

>>>Video: Transparent, soft, flexible speaker from ion gel

To build these speakers, the team used a transparent rubber sheet and added a layer of conductive salt water gel on each side. When a voltage is applied to the opposite corners of the gel layer, the area inside the rubber sheet will quickly bend, creating sound with frequencies from 20Hz to 20kHz. Due to the flexible and ionic properties of the material, the speaker can be stretched many times over the original size and still works well. Scientists believe that an improved version of the invention could be integrated into a computer or tablet screen to deliver tactile sound and feedback without the need for an external speaker.

A transparent speaker is a great thing. However, the main goal of the project is to demonstrate the ability to transmit ions by ion instead of electrons and the potential for application to electronic devices. In most cases, ionic substances tend to create a weak connection circuit when applied to them with a high voltage and potential that can trigger a chemical reaction that destroys the material. However, with Harvard University's system, rubber acts as a insulation layer, allowing scientists to better control voltage and speed up connections.

Jeong-Yun Sun (left) and Christoph Keplinger (right) - 2 scientists working on the project of transparent speakers from gel ions.

According to the research team, if ion conductors are perfect, they will potentially bring some advantages over the currently used conductors. A common problem with most flexible conductors is that their resistance increases when stretched, limiting performance in some electronic devices. Ion conductors on the other hand do not encounter this problem and can be stretched many times over the original area without affecting the internal circuit. Of course, ion conductors cannot meet the required resistivity in electronic devices up to the present time. However, if the goal is to create a flexible, flexible circuit, the ion conductor is a potential alternative. In addition, ion conductors can be made from commercially available transparent materials.

Christoph Keplinger, a co-author of the project, currently working as a postdoctoral researcher at Harvard SEAS, said: "We want to change people's views on the application of ion conductors. Our system It takes a lot of energy to function and you can integrate it everywhere when you need a soft, transparent, flexible material to respond to electrical stimuli - such as on the screen of a TV, laptop, or smartphone to create sound or tactile feedback in place and we can even think of smart windows. Most likely you can put this speaker on the window to achieve noise canceling effect with completely silent inner space ".

Biological connections

Besides the transparent and stretchable properties without affecting the circuit, ion gel in the speaker can transport ions similar to some biological systems, such as our nerves. This will most likely open a door to unify biological systems with man-made ion systems, such as muscle or artificial skin.

In the long run, researchers believe that their findings could lead to "more advanced and soft" devices with the ability to change shapes according to orders.

Keplinger said: "Our big vision is soft machines. Technically ionized systems can achieve many of the functions that our bodies have, such as feeling, transmitting a signal and launching. We really are approaching a kind of soft device like biological systems ".

Some examples of feasible projects they mentioned include focus-shift eyeglasses or robots that change shape to respond to a variety of tasks. Currently, the team plans to continue their research with experiments similar to many other ionic materials to find out which ones can work with longer charge and which materials can be bonded. to bring better connection.