A new mechanical sensing unit developed by a team led by Marc Serra-Garcia and Johan Robertsson harnesses sound vibrations to power itself, eliminating the requirement for batteries. This versatile and environment-friendly sensor, made from silicone, can recognize particular sounds for applications in facilities, medical gadgets, and market. Above is a prototype of the sound sensor. Credit: Astrid Robertsson/ ETH ZurichSensors utilized in monitoring infrastructure like structures and bridges, or in medical gadgets like prostheses for the hearing impaired, require a constant source of power. Typically, this power is provided by batteries, which are dealt with and changed when diminished, resulting in a big waste problem.An EU study anticipates that in 2025, 78 million batteries will end up in the rubbish every day.A new kind of mechanical sensing unit, developed by scientists led by Marc Serra-Garcia and ETH geophysics teacher Johan Robertsson, could now offer a remedy. Its developers have already gotten a patent for their invention and have actually now presented the principle in the journal Advanced Functional Materials.Certain acoustic wave trigger the sensing unit to vibrate” The sensor works simply mechanically and doesnt need an external energy source. It simply makes use of the vibrational energy contained in sound waves,” Robertsson says.Whenever a certain word is spoken or a specific tone or sound is created, the sound waves produced– and just these– cause the sensor to vibrate. This energy is then enough to generate a tiny electrical pulse that switches on an electronic gadget that has been changed off.The prototype that the researchers established in Robertssons laboratory at the Switzerland Innovation Park Zurich in Dübendorf has actually currently been patented. It can distinguish between the spoken words “3” and “four.” Because the word “4” has more sound energy that resonates with the sensing unit compared to the word “3,” it triggers the sensing unit to vibrate, whereas “three” does not. That indicates the word “4” might turn on a device or trigger further processes. Absolutely nothing would occur with “three.” Newer versions of the sensor should be able to distinguish in between approximately twelve various words, such as standard machine commands like “on,” “off,” “up,” and “down.” Compared to the palm-sized model, the brand-new versions are also much smaller– about the size of a thumbnail– and the scientists are intending to miniaturize them further.Metamaterial without problematic substancesThe sensing unit is what is called a metamaterial: its not the product utilized that provides the sensor its special properties, but rather the structure. “Our sensing unit consists simply of silicone and contains neither toxic heavy metals nor any rare earths, as conventional electronic sensing units do,” Serra-Garcia says.The sensing unit makes up dozens of similar or likewise structured plates that are connected to each other by means of small bars. These connecting bars imitate springs. The scientists used computer modeling and algorithms to establish the unique design of these microstructured plates and exercise how to attach them to each other. It is the springs that determine whether a particular noise source sets the sensing unit in motion.Monitoring infrastructurePotential usage cases for these battery-free sensing units consist of earthquake or structure monitoring. They could, for example, register when a building develops a fracture that has the best sound or wave energy.There is also interest in battery-free sensors for keeping an eye on decommissioned oil wells. Gas can escape from leakages in boreholes, producing a characteristic hissing sound. Such a mechanical sensing unit could detect this hissing and set off an alarm without constantly consuming electrical power– making it far cheaper and needing much less maintenance.Sensor for medical implantsSerra-Garcia likewise sees applications in medical devices, such as cochlear implants. These prostheses for the deaf require an irreversible power supply for signal processing from batteries. Their power supply lies behind the ear, where there is no space for large battery packs. That means the users of such gadgets need to change the batteries every twelve hours. The unique sensors might likewise be utilized for the constant measurement of eye pressure. “There isnt sufficient area in the eye for a sensing unit with a battery,” he says.” Theres a lot of interest in zero-energy sensors in market, too,” Serra- Garcia adds. He no longer works at ETH however at AMOLF, a public research institute in the Netherlands, where he and his team are fine-tuning the mechanical sensing units. Their aim is to introduce a solid model by 2027. “If we havent managed to bring in anybodys interest already, we might discovered our own start-up.” Reference: “In-Sensor Passive Speech Classification with Phononic Metamaterials” by Tena Dubček, Daniel Moreno-Garcia, Thomas Haag, Parisa Omidvar, Henrik R. Thomsen, Theodor S. Becker, Lars Gebraad, Christoph Bärlocher, Fredrik Andersson, Sebastian D. Huber, Dirk-Jan van Manen, Luis Guillermo Villanueva, Johan O.A. Robertsson and Marc Serra-Garcia, 09 January 2024, Advanced Functional Materials.DOI: 10.1002/ adfm.202311877.
Its developers have actually currently applied for a patent for their development and have now presented the concept in the journal Advanced Functional Materials.Certain noise waves trigger the sensing unit to vibrate” The sensor works purely mechanically and does not need an external energy source. Because the word “four” has more noise energy that resonates with the sensor compared to the word “3,” it causes the sensor to vibrate, whereas “3” does not. Compared to the palm-sized prototype, the new versions are likewise much smaller sized– about the size of a thumbnail– and the researchers are aiming to miniaturize them further.Metamaterial without troublesome substancesThe sensor is what is known as a metamaterial: its not the product used that offers the sensor its special residential or commercial properties, but rather the structure. “Our sensor consists purely of silicone and contains neither toxic heavy metals nor any rare earths, as standard electronic sensing units do,” Serra-Garcia says.The sensor makes up lots of similar or likewise structured plates that are linked to each other by means of small bars. It is the springs that determine whether or not a particular sound source sets the sensing unit in motion.Monitoring infrastructurePotential usage cases for these battery-free sensors consist of earthquake or structure tracking.