So nice to meet you. And I’m Tetsuhiko Teshima from German branch of MEI Laboratories. I’m working at the Technische Universitat Munchen to conduct wet experiment like using chemical and biological samples. So it’s great honor and pleasure for me to have a chance to share with you some topics about miniaturized bio-interfaces that I have been working on over the last six or seven years, I guess. So before starting, please let me introduce myself and my background. So I started to work in this company since this March, but until the last year, I was working in NTT Basic Research Laboratories that is located in Kanagawa, Japan.

And I have worked on basic nanoscience research. But when going back to the further, I was originally a student studying biology, especially infectious microbiology. And then I learned about the miniaturized fluidic system to manipulate single cells and MEMS (micro-electromechanical systems) technologies that is kind of a fabrication process for semiconductor devices. So, this background motivated me to start interdisciplinary work, especially about biomedical engineering at NTT Corporation. So in recent years, wearable electrodes have been developed to continuously monitor the vital data, including the heart rate, ECG, or EMG waveforms for rapid diagnosis and early stage treatment of disease.

So conventionally, rigid metals or metal-plated fibers have been widely used as the electrodes, but they lack flexibility and biocompatibilities, which results in the noise in obtaining data and the patient allergic reaction during the long-time years. So at NTT, we are working on the research and development of the conductive composite materials. So, due to its high flexibility and hydrophilicity and biocompatibilities, so these electrodes can successfully record ECG without any rashes and itches to the skin.

So now these wearable electrodes, called ‘hitoe’, are commercially available and further applied for not only the medical care and rehabilitation for the patients, but also for example, remote monitoring system of the workers, integration with these sportswear and entertainment show. But this product is originated from the basic scientific findings especially on the conductive polymers, PEDOT-PSS and silk fibers. So there was some mainly conducted by two key scientists: clinician doctor Tsukada, and chemist doctor, Nakashima. In order to realize this product, they try so many prototypes and make so many efforts to obtain the pharmaceutical probables for medical usage. So through this experience, we are going back to the original material science and research and making non-toxic interfaces with cells and tissues in order to seek new kind of development.

So, as a next challenge, I have focused on the electrodes that work inside the bodies. So we have the tissues and organs with electrical signals like heart and brain. So if implanted electrodes can work on these tissues, this helps us to increase the variety of the vital data like EEG. And also it can directly treat the targeted tissues as a surgical, too, like CRT pacing. So in this case, these biointerfaces should be populated in very humid environment and in non-toxic manner. They also should be transformed into soft, three dimensional structures, in order to fit the shape of cells and tissues because they have very complicated 3D structures.

So I decided to develop the basic electrode component that meets all of these requirements that is biocompatible for example, like 3D film-electrodes. So what I tried at first is to create a non-toxic, very soft and flexible flat-electrodes using the materials that are using the hitoe electrodes that is silk bundles and PEDOT-PSS. So, firstly, I dissolve the silk bundle to extract a specific protein and process into a palette shape using MEMS technologies, one of my main skills. So by adding the conductive polymers, PEDOT-PSS little by little, the palettes will gradually become blue but maintain the high optical transparency. Through this experiment, I discover a very unique materials scientific aspect of silk fibroin. So when PEDOT-PSS got added, the molecular structure and the confirmation of silk protein dramatically change from alpha helix to the beta sheet, and I focused this structure change, leads to the increase in conductivity compared with the PEDOT-PSS pristine films. By using the lithographic fabrication process, the films can be processed into very tiny shape, with same deviation as single cell lego.

So this electrode is made of the silk fibroin, the very cell-friendly protein. So the suspender cells prefer to adhere to their surface. So after attaching the cells on a surface, I can manipulate the cells while maintaining the adhesive properties and electrically stimulate the cells for the cold, very weak electrical signals from the cells. So in this step, we created a non-toxic, transparent, and very flexible films and film-based electrodes. But please note that they are 2D and they’re still not 3D.

So in the next step, I tried to investigate how to transform these same 2D film to 3D shape. So here, among two polymers I used, so I replace the PEDOT-PSS with different type of polymers, there is parylene, like this. So when the parylene is adhering to the silk fibroin layers so, the gradient of the mechanical stiffness is formed in the synchronous directions as shown here. And this gradient causes the driving force of same film folding, like this. So this is a, this is a movie of the self-folding bilayer films.

And you can see these rectangular patterns spontaneously transform into the cylindrical shapes. So just before folding, I suspended the cells on top of the films that is derived from the heart muscles. So the folding films, so here can gently rub the cells inside the tubes and you can incubate them safely more than for two weeks in order to reconstitute the self-beating, fiber-shaped muscle tissues, as shown here. So also these reconstituted tissues can be manipulated like building blocks by picking up and dissolving using glass capillaries.

So I believe these techniques has a potential to facilitate high-order self-assembly like artificial neural networks or tissue engineering. So I realized to transform the two different film to 3D shape. So I use this method to transform into 3D electrodes. So in the final step, instead of the silk fibroin, I focus on using extremely thin electrodes materials that is called graphene. So as I explained as extremely thin, so it consists of the only single layer of carbon atom.

So since they have just a single atom thickness, it has very high optical transparency and flexibility. So when the graphene was transformed to the parylene surface I found this bilayer was tightly bonded due to the strong molecular interactions and the graphene itself straight on the parylene surface, and this cell film becomes three dimensional electrodes, like [unintelligible] structures. So as you can see in this movie, like this. So just after releasing them from the service lead, it instantly undergoes a phase transition and collapses.

So since, this hexagonal molecular structure of graphene is distorted due to the folding process, so electrical characteristics dramatically change from firstly metallic to the semiconductor-like non-linear shape, shown here. Or interestingly, the curvature and direction of the cell folding can be well controlled with number of graphene, this and its crystalline directions. So when a merged layers graphene was transferred, the curvature radius become smaller and smaller. And when the single crystalline graphene was loaded on the surface of parylene, this bilayer was folded in one fixed same direction, especially along the arms [unintelligible] siding.

So by simply transferring the single carbon atom layer to the parylene surface, so we achieved the self-assembly of 3D transparent electrodes. In order to demonstrate biocompatibility of this graphene electrodes, we apply for the interface with neurons. So as there was a self-folding of silk fibroin, so the suspended neurons are encapsulated in the self-folded graphene tubes, like this. So I made it a very tiny holes on the films. So the encapsulated neurons can uptake the nutrition and oxygen through this pore.

So I culture the neurons for, without any damage, to the cells, and they exhibit cell-cell contact for tissue-like structures and they elongate their neurites and axon to the outside through this pore. Therefore, the embedded neurons properly exhibit cell-cell interaction and drive intrinsic morphologies and function, which shows achievement of biocompatibility of the graphene electrodes.

So in summary, we have been working on producing tiny 3D electrodes, step-by-step, using only four materials. For example, by mixing conductive polymer, PEDOT-PSS with silk fibroin, I made transparent and flexible 2D electrodes. By making a bilayer with silk fibroin with parylene, I demonstrated the self-assembly from 2D film to 3D shape. Finally, by transferring the graphene to paralyene, we could assembly tiny 3D electrodes. So in the future, we will continue to work on making bioelectrodes from the material science and biological viewpoints. However, these two approaches are not sufficient for the research or the bioelectronics.

And we especially needed the technology of electrochemical assessment of fabricated electrodes and the method to lead up of obtained vital data and manipulation and analysis of obtained data. Therefore, I belong to both of the TUM and NTT research, in order to achieve the four systems. So when I look over the world R&D of the bioelectronics, especially implantable electronics are very active, regardless of the university and industry.

So firstly, John Rogers’ group in University of Illinois, in United States, started to advocate about the implantable, flexible bioelectronics, more than 10 years ago. So now the research on, about it, is rapidly growing all over the world, not only US, but the Asia and Europe. So, the industrial community also tend to participate in this field. So I really hope to contribute to the scientific achievement and the creation of industry from the German basis, by making the most of my experience and cooperation with Japan and American side.

So finally, I like to introduce my colleagues in TUM. So they are loved members and he, he is supervisor, Professor Bernhard Wolfrum, especially of the electrochemistry and electrochemical engineering process for biomedical application. So I’m so happy to work with this wonderful team and also appreciated the daily support of the members in NTT research in United States. Finally, let me just conclude by acknowledging my supervisor, mentors, Professor Wolfrum, Director Tomoike, and Dr. Alexander.

And also the member from NTT who always support me, especially Mr. Kikuchi, Dr. Nakashima, Tsukada fellow, Director Goto, Dr. Yamamoto, and Director Sogawa. Finally, let me thanks Professor Offenhausser from Julich, for his kind assistance and introduction to this wonderful collaboration schemes. So, that’s all. And I hope this presentation was useful to you. Thank you very much.