Newly developed sensors could be added to fitness wristbands in order to detect underlying health problems through non-invasive testing of bodily fluids. A team at the King Abdullah University Of Science & Technology (KAUST) have created a stretchy patch that can analyze sweat for critical biomarkers.
Human perspiration contains trace amounts of organic molecules that can act as measurable health indicators: glucose fluctuations, for example, may point to blood sugar problems, while high levels of lactic acid could signal oxygen deficiencies.
To detect these molecules, flexible prototypes have been developed that sit on the skin and direct sweat toward special enzyme-coated electrodes. The specific nature of enzyme-substrate binding enables these sensors to electrically detect very low concentrations of target compounds.
One obstacle with enzyme biosensors is that they typically have relatively short lifetimes.
“Even though human skin is quite soft, it can delaminate the enzyme layer right off the biosensor,” said Yongjiu Lei, a Ph.D. student at KAUST.
The new wearable system can handle the rigors of skin contact and deliver improved biomarker detection.
The team found that inside the laser, the different frequencies of light beat together to generate microwave radiation. The light inside the cavity of the laser caused electrons to oscillate at microwave frequencies—which are within the communications spectrum.
“If you want to use this device for Wi-Fi, you need to be able to put useful information in the microwave signals and extract that information from the device,” said Marco Piccardo, first author of the paper.
The first thing the new device needed to transmit microwave signals was an antenna.
The researchers etched a gap into the top electrode of the device, creating a dipole antenna (like the rabbit ears on the top of an old TV).
They then modulated the frequency comb to encode information on the microwave radiation created by the beating light of the comb. Using the antenna, the microwaves are radiated out from the device, containing the encoded information. The radio signal is received by a horn antenna, filtered and sent to a computer.
The researchers also demonstrated that the laser radio could receive signals. The team was able to remotely control the behaviour of the laser using microwave signals from another device.
“This all-in-one, integrated device holds great promise for wireless communication,” said Piccardo. “While the dream of terahertz wireless communication is still a way away, this research provides a clear roadmap showing how to get there.”
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