New generation of touch devices

A blind fish has developed a special motion sensing skill, which may be a prerequisite for a new generation of sensors that work better than ultrasonic sensors.

Although the fish Astyanax fasciatus does not see anything, they feel the environment and the movement of the water around them with the dense hairs secreted from the body. Their ability to detect underwater objects and orientations in their light-free environment inspired a group of scientists to mimic the hair structure of live fish in this row.

While fish use feathers to detect obstacles, avoid predators, and locate predators, researchers believe the sensors they are developing may have many underwater applications, purses. such as port security, surveillance, tsunami warnings, automatic underwater orientation, and marine research.

Vladimir Tsukruk, professor at the School of Materials Science and Engineering at Georgia Technological University, said: 'These hair cells are like very sensitive sensors, like the device we use to weigh equal and hear in person. Deviations or deviations of hairs containing thickeners measure important information. These hairs are more efficient than ultrasonic sensors that require a lot of space, sending strong sound waves that could be harmful to the environment. '

In a speech at the meeting of the American Physical Society, researchers from Georgia Tech described their motion-sensing device that mimics the blind fish that live in caves. The research was funded by the Defense Research Agency (DARPA).

Tsukruk and graduate student Michael McConney and Kyle Anderson perform preliminary experiments with an artificial touch cell made of SU-8, a conventional epoxy polymer capable of solidifying, based on micromachining Generate regular CMOS. They found that this artificial cell was unable to detect the hydrodynamic dynamics sensibly and at a distance. Artificial hair cells need solid shells - called cupula - to overcome these challenges.

Tsukruk, who holds an important position in Georgia Tech University's School of Polymer, Fiber and Textile Arts School, said: 'After covering hair cells with synthetic cupula, micro-touch devices are capable of detecting find better than blind fish. The fish may know the currents are slower than 100 micrometers per second, but our system is able to recognize flows of several micrometers per second. Adding to the cupula allows us to detect smaller fluctuations and expand the hydrodynamic range '.

The optical micrograph of maybe a blind fish living in a cave shows a row of cupula. This fish uses feathers (hair) to identify obstacles, avoid predators and identify prey. (Photo: Michael McConney)

In addition, the hydrogel shell protects the micro-sensor and increases its resistance to deformation due to pressure.It also helps the device better adapt to the marine environment, resistant to corrosion and development of microorganisms.

Before the team began synthesizing gel-like materials in the lab, they used optical microscopes and fluorescence microscopes to determine the size, shape and properties of the true cupula of fish. above. A kind of cupula they discovered was cylindrical, with a height of 5 times the diameter,.

To create a synthetic cupula in the lab, McConney added a solution of poly (ethylene glycol) tetraacrylate dissolved in methanol directly onto the hair-sensing fiber. When the first drop dries, he continues to add other drops one after another to form the hydrogel structure. When the structure of the cupula was dry, McConney exposed it to ultraviolet light to form a three-dimensional network.

McConney said: 'The method of adding one drop at a time to pehps we control the width and height of the cupula and the distance from the bottom of the cupula to the root of the hair'. While the study found that placing the nearest synthetic cupula with the induction root would reinforce the durability and longevity of the capula, they also found that the ability to detect purple was best when the cupula structure started in the middle. hair fibers and then spread more than 50% hair fibers. They achieved the best results with 550-millimeter-long touch hairs with cupula starting at 275 millimeters on the hair shaft and lasting more than 275 millimeters, the total length of the structure was 825 millimeters.

So far, researchers have built 8 types of micro-sensors and are capable of detecting purple vibrations in water. They are currently looking for partners to scale up the research by making thousands of sensors and testing them in real environments.

Cheryl Coomb of Bowling Green State University and Chang Liu of the University of Illinois also contributed to the study.