Flexible and adaptive microelectronics is considered an innovation driver for new and more effective biomedical applications. These include, for example, the treatment of damaged nerve bundles, chronic pain, or the control of artificial limbs. For this to work, close contact between electronics and neural tissue is essential for effective electrical and mechanical coupling. In addition, potential applications arise from the production of tiny and flexible surgical tools.
An international team led by Prof. Dr. Oliver G. Schmidt, head of the Institute for Integrative Nanosciences at the Leibniz Institute for Solid State and Materials Research (IFW) Dresden and holder of the Professorship of Materials for Nanoelectronics at Chemnitz University of Technology and initiator of the Center for Materials, Architectures and Integration of Nanomembranes (MAIN), as well as Boris Rivkin, a PhD student in Prof. Schmidt’s group, has now demonstrated for the first time that such adaptive microelectronics are able to position themselves in a controlled manner, manipulate biological tissue, and respond to their environment by analyzing sensor signals.
Different properties for dynamic processes
Until now, it has not been possible for microelectronic structures to both sense and adapt to their environment. Although there are structures with a strain sensor that monitor their own shape, microelectronics with magnetic sensors that orient themselves in space, or devices whose motion can be controlled by electroactive polymer structures, a combination of these properties for application in a dynamic changing organism at the micrometer scale, i.e. well below a millimeter, has not been reported so far.
Artificial muscles generate movement
The movement and reshaping of adaptive microelectronics is achieved by means of artificial muscles, the so-called "actuators". These generate movement by ejecting or absorbing ions and can thus reshape the polymer film.
This process is based on the use of the polymer polypyrrole (PPy). The advantage of this method is that manipulation of the shape can be carried out in a targeted manner and with already very low electrical bias (less than one volt). The fact that artificial muscles are also safe for use in organic environments has already been demonstrated by other groups in the past. This involved testing the performance of the micromachines in various environments relevant to medical applications, including cerebrospinal fluid, blood, plasma, and urine.
Next: microelectronic robots
The team from Dresden and Chemnitz expects that adaptive and intelligent microelectronics will be developed into complex robotic microsystems in the medium term. Boris Rivkin says: "The crucial next step is the transition from the previously flat architecture to three-dimensional micro-robots. Previous work has demonstrated how flat polymer films can reshape into three-dimensional structures through self-organized folding or rolling. We will add adaptive electronics to such materials to develop systems such as cmicro-catheters, tiny robotic arms, and malleable neural implants that act semi-autonomously following a digital instruction."
Dr. Daniil Karnaushenko, group leader in Prof. Oliver Schmidt's team, adds, "Such complex microrobots will require a large number of individual actuators and sensors. To effectively accommodate and use electronic components in such a density is a challenge because more electrical connections are needed than space is available. This will be solved by complex electronic circuits that will be integrated into adaptive microelectronics in the future to pass the appropriate instructions through to the right components."
This work also contributes to the emerging field of robot-assisted surgery, which could enable less invasive yet more precise procedures. Smart surgical tools that generate reliable feedback about their shape and position could become indispensable in treating delicate tissue.
The results were published Advanced Intelligent Systems.