A new device listens to objects and bodies to measure temperature.
We have already learned that many devices listen to us, and this is a matter of concern for our privacy.
But this device listens differently. And you can be sure it doesn’t invade your privacy.
Hot objects not only shine, but also “hum” slightly. The buzz is generated by the rapid movement of the particles that make up the hot object.
If human ears were loud enough to hear this noise, “it would sound radio-static,” says Tom Purdy of the University of Pittsburgh. “The hotter an object becomes, the louder the sound.”
Hence the idea of a thermometer that listens to you.
Purdy with Robinjeet Singh of the University of Maryland in College Park, they created an acoustic thermometer which detects the intensity of the sound generated by the heat that your body or any surrounding object emits.
The heart of the device is a one-square-millimeter sheet of silicon nitride. That sheet is suspended in a window cut in the center of a silicon chip, which transmits sound waves better than air.
In the experiments, physicists deposited stains of epoxy material on the surface of the chip around the silicon nitride sheet.
When heated by a laser, each epoxy drop emitted sound waves that dripped through the chip to the sheet, causing the sheet to vibrate.
The hotter the epoxy, the stronger its sound waves and the more intense the vibrations of silicon nitride.
The researchers were able to track the movement of the sheet and therefore the temperature of the epoxy, using a laser beam on the sheet and by measuring the reflection angle of the beam, as reported by Singh and Purdy in the Physical Review Letters.
Purdy hopes that this new thermometer could be used in the future for quantum computing devices, which need to operate at very low temperatures.