A team of scientists from Saint Petersburg Electrotechnical University “LETI” developed a computer model to study the internal processes in the electrical components of microbots and to predict their reactions to different conditions. The work was supported by a grant from the Russian Science Foundation, and an article about it was published in the Micromachines journal.
To work with nano- and microsized details or in hard-to-reach places, modern-day scientists use microbots. For example, in medicine, they are used for target drug delivery or non-invasive surgeries.
“Most polymers are flexible, lightweight, and easy to manufacture and process. In addition to these properties, an ionic polymer-metallic composite material (IPMC) is also able to actively deform in response to several volts of voltage applied to electrodes. Because of that, it can be used as a material for soft robotized drives, artificial muscles, and dynamic sensors for bionic engineering,” said Ivan Khmelnitskiy, Assistant Professor at the Department of Micro- and Nanoelectronics of LETI.
An ionic polymer-metallic actuator (activation device) is a mechanism that consists of a polymer membrane covered with a conductive layer of metal on both sides and electrodes with 1V to 5V voltage attached to it. Before use, the polymer is saturated with water. The liquid starts moving under the influence of the electric field, increasing the pressure on one electrode and reducing it on the other. This pressure difference causes IPMC to curve.
Composite materials of this kind can be used to manufacture various microbots. Therefore, it is extremely important to understand the processes that happen inside them under the influence of applied voltage to accurately predict the reaction of the membrane. To do so, scientists use complex mathematical models that calculate the internal processes based on the initial observational data. However, most mathematical models require a lot of computational resources and are quite expensive. Therefore, scientists are looking for optimization methods that would simplify the research and development of microdevices.
A team of researchers from LETI created a computer model that requires minimal resources to program an algorithm and create a simulator to monitor all necessary processes. The model consists of adjoint differential equations that describe the transportation of charged particles (ions) and water molecules in an ion-exchange membrane, as well as the electrostatic field inside it and the mechanical deformation of the mechanism. To calculate these values, the scientists added geometric characteristics (length, width, layer thickness, etc) and physical properties (diffusion coefficient, ion concentration in the polymer, layer density, etc) to the model.
“Using the novel computational modeling software, we calculated and studied the spatial distribution of ions and water molecules in an IPMC polymer membrane. The optimized model suggested by our team provides for the monitoring of ion transportation dynamics in the composite material depending on membrane parameters and control voltage,” says Eugeny Ryndin, Professor of the Department of Micro- and Nanoelectronics of LETI
“Our work supports calculations with complex modern-day mathematical models and provides for international-level results, but requires quite simple equipment: a personal computer with free software. We hope that the simulation methodology described by our team would spur further developments in this field,” commented Anton Broyko, Assistant Professor at the Department of Micro- and Nanoelectronics of LETI.