Graphene is mixed into plasticine to transform into an ultra-sensitive pressure sensor

• Categories:Industry information
• Time of issue:2017-03-13 17:06

(Summary description)　　A sensor made of graphene and plasticine can monitor blood pressure in real time for 24 hours. 　　Just add a little graphene to turn the plasticine into a pressure sensor. This kind of sensor is extremely sensitive, not only can monitor the human pulse, it can even detect the footsteps of a small spider. 　　This graphene plasticine is called "G-putty", and the developers hope to develop devices that continuously monitor blood pressure based on it. In addition, G-putty has shown its ability to repair itself, indicating that it may become a smarter graphene composite material. 　　Since graphene was first isolated in 2004, researchers have tried to add these thin layers of carbon atoms to various materials, hoping to create composite materials that can benefit from the high strength and excellent conductivity of graphene. But surprisingly, almost no one has tried to mix graphene with viscoelastic materials like plasticine. Plasticine exhibits the characteristics of elastic solid and liquid at the same time. For example, putting a piece of plasticine on a hole, it will slowly leak through. 　　Conor Boland, a researcher at the Jonathan Coleman Nanotechnology Laboratory at Trinity College Dublin, said he was curious about what would happen when graphene and plasticine were mixed. "I would like to say that the idea was carefully conceived, but it is not," Coleman said with a smile, "because we happen to have such a tradition of using household appliances in scientific research." (His team said It was discovered in 2014 that graphene can be obtained by quickly stirring graphite with a stirrer in the kitchen.)   [Explanation] Jonathan Coleman and his son are playing with G-putty. Image source: Trinity College Dublin   　　The researchers mixed graphene sheets about 20 atoms thick and 800 nanometers long with homemade plasticine (an organosilicon polymer) to obtain conductive dark gray G-putty. A key feature of this material is that even if the researcher applies only a weak pressure, its electrical resistance will change greatly. This plasticine is at least 10 times more sensitive than other nanocomposite sensors. 　　The researchers connected a piece of G-putty to a wire and placed it on a student's neck, and his carotid pulse could be clearly measured by the change in electrical resistance. In fact, the pulse profile is very fine and can be converted into accurate blood pressure readings. The sensor can also be placed on a student's chest to monitor breathing. In addition, it’s a bit weird that it can also record every step of a spider that weighs only 20 milligrams. 　　"They fully demonstrated the versatility of this material," said Vincenzo Palermo, a materials scientist at the National Research Council of Italy. "I think this is an amazing work and very novel." The research was published in Science. 　　Coleman's research team found that graphene flakes formed a conductive network in the plasticine, and the deformation of the plasticine would destroy the network, resulting in a rapid increase in resistance. Then, due to the low viscosity of G-putty, the graphene flakes can be moved back to the original position and reorganized the network. "This is a self-healing phenomenon." Coleman explained. 　　Coleman is already in talks with medical device companies interested in using G-putty for continuous physiological monitoring. For example, patients usually need to wear a heavy wristband to measure blood pressure, and only get an instantaneous reading. However, G-putty is a cheap and compact non-invasive sensor that allows patients to easily monitor blood pressure at home. 　　Sanna Arpiainen is a senior scientist researching graphene. She works at VTT, a large contract research organization near Helsinki. She said that some companies, such as Nokia, are interested in the health applications of graphene sensors. But she warned that before commercializing G-putty, a series of obstacles need to be overcome-including proving that it can be mass-produced and testing to evaluate its long-term performance. Palermo agrees: "For practical applications, you need it to run in the same way thousands of times." 　　When conducting the G-putty experiment, the researchers encountered an unexpected obstacle. Boland wanted to perform a comparison test between the two spiders, but he found that he didn't pay attention, the larger spider had swallowed its little buddy. "He didn't expect this kind of difficulty in working with animals," Coleman said.