Researchers at the University of Houston report a breakthrough in materials science and technology with the development of an electrochemical actuator that uses specialized organic semiconductor nanotubes (OSNTs).
The actuator is currently in the early stages of development and will be an important part of research that will contribute to the future of robotics, bioelectronics and biomedical science.
“Electrochemical devices that convert electrical energy into mechanical energy can be used in a wide variety of applications, from soft robotics and micropumps to autofocus microlenses and bioelectronics,” said Mohammad Reza Abidian, associate professor of biomedical engineering at UH Cullen College of Engineering . He is the corresponding author of the article “Organic Semiconductor Nanotubes for Electrochemical Devices”, which was published in the journal Advanced Functional Materials and describes the discovery in detail.
Significant motion (which scientists define as actuation and measure as strain strain) and fast response times have been hard-to-reach goals, especially for electrochemical actuator devices that operate in liquid. This is because the drag force of a liquid restricts the movement of an actuator and limits ion transport and accumulation in electrode materials and structures. In Abidian’s laboratory, he and his team refined the methods to circumvent these two stumbling blocks.
“Our electrochemical component made of organic semiconductor nanotubes has a high actuator performance with fast ion transport and accumulation and adjustable dynamics in liquid and gel polymer electrolytes. This device shows excellent performance including low power / load, large deformation, quick response, and excellent actuation stability, ”said Abidian.
This outstanding achievement comes from the enormous effective surface of the nanotube structure. The larger area facilitates ion transport and accumulation, which leads to high electrical activity and durability.
“The low power / strain values for this OSNT actuator, even when operated in liquid electrolyte, represent a profound improvement over previously reported electrochemical actuators that operate in liquid and air,” said Abidian. “We evaluated the long-term stability. This organic semiconductor nanotube actuator showed superior long-term stability compared to previously reported actuators based on conjugated polymers that are operated in a liquid electrolyte. “
Abidian included Mohammadjavad Eslamian, Fereshtehsadat Mirab, Vijay Krishna Raghunathan, and Sheereen Majd, all from the Department of Biomedical Engineering at UH Cullen College of Engineering.
The organic semiconductors used, so-called conjugated polymers, were discovered in the 1970s by three scientists – Alan J. Heeger, Alan MacDiarmid and Hideki Shirakawa – who received the Nobel Prize in 2000 for the discovery and development of conjugated polymers.
In order for a new type of actuator to overshadow the status quo, the end product not only has to prove to be highly effective (in this case both in liquid and gel-like polymer electrolyte), but also has to be durable.
“To demonstrate potential applications, we designed and developed a moveable neural probe in the micrometer range based on OSNT microactuators. This microprobe has the potential to be implanted in the brain, where neural signal recordings that are compromised by either damaged tissue or neuron dislocation can be improved by adjusting the position of the movable micro-cantilevers, ”Abidian said.
The next step is animal testing, which will soon be conducted at Columbia University. First results are expected by the end of 2021, with longer-term tests to follow.
“Given the achievements to date, we believe that these new OSNT-based electrochemical devices will help advance the next generation of soft robotics, artificial muscles, bioelectronics and biomedical devices,” said Abidian.
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