When a small insect lands on a person’s hand, the nerve endings in the skin sense this light touch with precision, and in the next moment the same hand can firmly grasp a heavy solid object without losing its sense of texture and detail.
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This natural ability of human skin, which combines a delicate sensitivity to the simplest touches with the ability to withstand high mechanical pressures, has remained an engineering dilemma for designers of flexible electronic devices.
The prevailing rule in sensor engineering imposed a difficult trade-off: either a sensor that is highly sensitive to light touches quickly becomes saturated and loses its ability to measure at the slightest increase in load, or a sensor that can withstand heavy weights and pressures but is unable to detect subtle touch movements.
Recently, a Chinese research team successfully addressed this trade-off by developing a flexible pressure sensor that combines high sensitivity and a wide operating range in a single device. The team published their findings in the International Journal of Extreme Manufacturing.
“The significance lies in combining high sensitivity and a very wide operating range in one device,” said Dao-Chi Xin, a professor at Shanghai Jiao Tong University and one of the lead researchers of the study, in exclusive statements to Al Jazeera Net. “In the benchmarking comparison presented in the research paper, this combination puts our sensor at a level of outstanding performance compared to modern ion pressure sensors.”
This laser is characterized by emitting extremely short bursts of light lasting for fractions of a quadrillionth of a second. The advantage of these ultra-high pulses lies in their ability to precisely and coldly ablate material, as the material vaporizes from the metal surface faster than the time it takes for heat to spread to adjacent areas in the foil, thus preventing edge melting or damage to the desired geometric shape.
This type of precision laser is used to form regular pyramidal frameworks at the micro scale, while the nanoparticles produced by the laser ablation process are redeposited to form structures at the nano scale.
"The two levels work together," Dao-Chi adds. "The micro-pyramids provide mechanical flexibility and formability, while the nanostructures greatly increase the effective contact area, enabling the sensor to achieve high sensitivity and an extremely wide pressure range simultaneously, without the need for complex, multi-step precision manufacturing processes."
During instantaneous photoevaporation, a localized cloud of plasma loaded with ejected metal atoms is created, which quickly condenses and is deposited on the surfaces and tops of those pyramids, forming tiny nano-clustered clusters ranging in diameter from 100-700 nanometers.
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