Name: thin film composite silicon elastomers for cell culture and skin applications: manufacturing and characterization
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Martin Danner ist bekannt für seine Hilfe bei der Vorbereitung von Proben und Definition der Zelle Kultur Verfahren anerkannt. Die Autoren möchten Biesterfeld Spezialchemie GmbH (Hamburg, Deutschland), vor allem Robert Radsziwill für kontinuierliche Unterstützung und Diskussionen zu danken. Die Forschung führt zu diesen Ergebnissen wird finanziell vom European Research Council unter EU Fp7 (FP/2007-2013) ERC Grant Agreement n. 340929.

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Das Design der composite-Strukturen ermöglicht die einfache Anpassung der Materialeigenschaften, wie des Elastizitätsmoduls oder die Dicke der Proben. Elastizitätsmodul von PDMS kann effektiv in einem breiten Spektrum durch das Mischungsverhältnis zwischen den beiden Komponenten zu verändern oder die Herstellung der Mischungen mit einem unterschiedlichen Silikon Elastomer30,31geändert werden. Die beschriebenen Methoden sind nicht beschränkt auf die PDMS in dieser Untersuchung verwendet, aber vor allem die selbstklebende Leistung hängt stark von der spezifischen Art verwendet. Ein wichtiger Schritt innerhalb dieses Protokolls ist der Herstellungsprozess von Verbundfolien (Abbildung 1). Es zeigte sich, dass die Dicke der Filme erheblich beeinträchtigt die Haftung Verhalten der Filme auf verschiedenen Substraten, einschließlich Haut (Abbildung 5 und Abbildung 6). Neben der Foliendicke Zeit und Temperatur während des Trocknungsprozesses wirkt sich die Materialeigenschaften32. Parameter wie die Dicke der Polymeren Schichten müssen daher sorgfältig angepasst und überprüft werden.
Analyse der selbstklebenden Eigenschaften dünner Schichten erfolgte mit Normalkraft Adhäsion Messungen mit zwei Glassubstraten mit verschiedenen Rauheit der Oberfläche bis zu Ra = 0.338 µm (Abbildung 3). Im Allgemeinen wirkt Rauheit deutlich die Haftung von Oberflächen, insbesondere von elastischen Materialien33,34. Die Rauheit des Glases kann leicht variiert werden, durch Schleifen mit Schleifpapier verschiedener Schroffheit Größen, daher erlauben die Herstellung von Substraten, die höhere Rauheit Werte21ausstellen. Darüber hinaus andere Materialien, z.B. Epoxidharz für die Herstellung von Substraten15,35einsetzbar. Dies könnte eine wichtige Modifikation Strategie des vorliegenden Protokolls sein. Zum Beispiel wenn Substrate mit verschiedenen Oberflächen freie Energien benötigt oder spezielle sind Topographien erforderlich. Hier wurden abziehen Stress und der Trennung von den Dünnschichten des PDMS und SSA hergestellt mit einem maßgeschneiderten Setup (makroskopische Adhäsion Messgerät (MAD, Abbildung 4)) analysiert. 36 optische Ausrichtung des Substrats und Eindringkörper ist ein entscheidender Schritt für die Analyse der Messergebnisse. Einstellung des Neigungswinkels muss daher mit dem Goniometer, so präzise wie möglich durchgeführt werden. Dies kann mit ausreichender Genauigkeit erreicht werden, indem Sie manuell das Substrat in Kontakt mit der filmoberfläche bis ein horizontale Kontakt entsteht.
Das aktuelle Protokoll wurde die Haltezeit auf eine Sekunde (Abbildung 5 und Abbildung 7) konstant gehalten. Vor allem für die Untersuchung der Klebstoff Leistung einen elastischen Film auf eine grobe Substratoberfläche stellt eine Erweiterung der Haltezeit Zusatzinformationen. Zum Beispiel wurde eine Zunahme der abziehen Stress mit zunehmendem Haltezeit gemeldeten8. Neben der Messungen in das aktuelle Protokoll, andere Methoden könnte zum Beispiel Peel Tests durchgeführt werden ermöglicht eine umfassendere Untersuchung der Haftung Leistung37.
Die Hafteigenschaften von Verbundfolien ausstellen anderen Film, die Dicke des Klebers weiche Haut ermittelt wurden (Abbildung 7). Unsere Ergebnisse sind in Übereinstimmung mit veröffentlichten Daten zeigen, dass eine Abnahme der Film Dicke führen zu einer Erhöhung der Belastung abziehen wie die Entbindung, d.h., das Verhältnis zwischen Durchmesser und Film Substratdicke, erhöht38,39 . Basierend auf diesen Ergebnissen und die Daten, die in Abbildung 7dargestellt, schließen wir, dass Verbundfolien mit einer Gesamtdicke von ca. 100 µm (Dicke der SSA-Schicht von ca. 60 µm aufgetragen zu einem PDMS-Film mit einer Dicke von ca. 40 µm) günstige Adhäsion p ausstellen Roperties auf rauen Oberflächen.
Als nächstes Experimente im Zusammenhang mit der biologischen Charakterisierung auf unberührten Verbundfolien durchgeführt wurden und Plasma behandelt Verbundfolien (Abbildung 8). Plasmabehandlung von Silikon-Elastomeren ist eine häufig angewandte, vielseitige Technik, um die hydrophilen Eigenschaften von Oberflächen und Förderung der zellulären Anlage und Mobilfunk Verbreitung40,41zu erhöhen. Silikone sind bekannt für ihre geringe Toxizität und hohe-Kompatibilität aber enthält möglicherweise Restmonomere oder Katalysatoren, die physiologische Prozesse, was auch zu Zytotoxizität42,43beeinflussen könnten. In die Experimente, die wir beobachtet haben, weniger als 5 % Zytotoxizität mit LDH Version als Indikator und ein Trypan blau-Ausschluss-Assay. Im vorgestellten Protokoll der gesamten zellulären Bevölkerung getrennt zellulären Aggregate einschließlich Form, die die Oberfläche für die Verbreitung Analyse (Abbildung 9 b) analysiert wurde. Eine Änderung des Protokolls könnte mehr differenzierte Ergebnisse produzieren. Für jede Probe konnte der Überstand mit freistehenden zellulären Aggregate auf einem separaten Reaktionsgefäß übertragen und nicht in Kombination mit der Zellen enzymatisch aus der Polymeroberfläche entfernt. Dies ermöglicht die genaue Beurteilung der Zellen an der Oberfläche befestigt und schließlich offenbaren eine genauere Bestimmung des Einflusses der Polymere auf die zelluläre Klebevorgang. Neben den hier vorgestellten Immunocytochemical Methoden möglicherweise Zellen für die Untersuchung mit Immunoblot Methoden, so dass eine detaillierte quantitative Bewertung der Proteinexpression geerntet werden.
Zusammenfassend haben wir Herstellungsbedingungen für die Herstellung von dünnen Elastomeren Verbundfolien für Anwendungen in der fortgeschrittenen Kultur Zellforschung etabliert. Darüber hinaus besitzen diese Dünnfilme hohen Anpassungsfähigkeit auf Haut, Rauheit, anspruchsvolles Design der Haut Klebstoffe ermöglichen.

In diesem Protokoll werden detaillierte Methoden für die Herstellung von dünnen Elastomer Filme vorgestellt. Die allgemein verfügbaren Arzt Klinge Technik wurde für die Herstellung von dünnen Verbundfolien eingesetzt. Die Herstellungstechnik wurde auf Polyethylenterephtalate (PET) Folien, spätere Produktion dieser Filme in großem Maßstab durchgeführt. Schwerpunkt dieses Protokolls ist die Bewertung der Reproduzierbarkeit, präzise Herstellung von den verschiedenen Schichten der Verbundfolien und Bestimmung der biologischen und Adhäsion Eigenschaften des endgültigen zusammengesetzte Patches. Die Silikon-Elastomer-poly-(dimethylsiloxane) (PDMS) wird weitgehend verwendet in der biomedizinischen Technologie, einschließlich der Herstellung von Haut-Klebstoffen, Mikrofluidik Anwendungen und zusätzliche Forschung Felder1,2,3 ,4. Vor kurzem, eine andere Unterklasse von PDMS, so genannte weiche Haut Klebstoffe (SSAs) wurden eingeführt, insbesondere für sanfte Haut kleben und de-bonding.
Silikon-SSAs sind Vinyl funktionalisiert Elastomere, abweichend von Analog Polymere durch den Mangel an Kieselsäure5zu stärken. Ähnlich wie bei anderen PDMS, SSA kann Elastizitätsmodul in einem breiten Spektrum von modulierenden Vernetzer Konzentration oder heilende Zeit6,7,8angepasst werden. Diese Veränderung des Elastizitätsmoduls von Siliconelastomeren die klebtechnischen Eigenschaften des Materials erheblich beeinträchtigt und hat auch tiefgreifende Auswirkungen auf die prokaryotischen und eukaryotischen Zellen kultiviert auf der Oberfläche9,10 , 11. auf der Zellebene biologische wurde gezeigt, daß Eukaryotische Zellen reagieren auf den Signalpegel Transduktion zu einer Modulation der Matrix Elastizität oder Dicke der Oberfläche9,10,12 ,13,14. Daher ein breites Interesse in Zelle Kultur Anwendungen von Polymeren mit einstellbaren mechanischen Eigenschaften vorhanden. Wichtig ist, bietet intrinsisch niedrige Oberflächenenergie von Siliconelastomeren basiert nicht optimale Bedingungen für die Zellkultur von eukaryotischen Zellen. Sauerstoff-Plasma-Behandlung ist eine weit verbreitete Technik, PDMS niedrige Oberflächenenergie vorübergehend, führt zu einer Steigerung der Haftzugfestigkeit erhöhen verringerte Oberfläche Adsorption von Molekülen, während parallel Anlage, Verbreitung zu fördern und Verbreitung von eukaryotischen Zellen15,16,17,18.
Neben den Materialeigenschaften beeinträchtigt der Oberflächentopographie erheblich, zelluläre Adhäsion und die selbstklebende Interaktion zwischen zwei Materialien19,20,21,22. Rauheit der Oberfläche hat verschiedene Auswirkungen auf die Kontakt zwischen zwei Flächen: Reduktion der Kontaktfläche, hohe gespeicherte elastische Energie rund um Unebenheiten sowie Einfluss auf die Rissausbreitung Haftfestigkeit23, verändern kann 24. Haftung von selbstklebenden Folien auf die menschliche Haut ist ein aufstrebendes Gebiet der Anwendung, z. B. Wundauflagen, Fixierung der EKG-Elektroden oder andere tragbare elektronische Geräte25,26,27, 28. Um den Klebstoff Leistungsmessung von selbst-Klebstoffen in Bezug auf Topographie können Glassubstrate mit unterschiedlichem Grad der Rauheit im normalen Adhäsion Messungen8,21verwendet werden. Hier wurden zwei Glassubstraten ausgewählt, um die Hafteigenschaften von Polymerfolien untersuchen. Zeichneten sich erste, zusammengesetzte Filme mit einer Trägerschicht PDMS im Mischungsverhältnis 10: 1 Gewicht Teile mit unterschiedlichen Mischungsverhältnis von PDMS abgedeckt. In einem zweiten Schritt wurde eine Klebeschicht SSA mit gleichem Gewicht Mengen beider Komponenten und mit unterschiedlichen Schichtdicken auf PDMS Vorfilm vorbereitet.

<table><tbody><tr><td>2-Propanol, 97%</td><td>Stockmeier Chemie</td><td>1000452610000</td><td>Isopropanol</td></tr><tr><td>Abrasive diamnod hand pad</td><td>Bohle</td><td>MO 5007522</td><td>Grit: 220</td></tr><tr><td>Accutase</td><td>Capricorn Scientific</td><td>ACC-1B</td><td></td></tr><tr><td>Albumin Fraktion V</td><td>Roth</td><td>0163.2</td><td>BSA</td></tr><tr><td>Alexa Fluor 488 Phalloidin</td><td>ThermoFischer Scientific</td><td>A12379</td><td>highly toxic</td></tr><tr><td>Aquamount</td><td>Polysciences</td><td>18606-20</td><td>water soluble mounting medium</td></tr><tr><td>CytoTox-ONE Homogeneous Membrane Integrity Assay</td><td>Promega</td><td>G7890</td><td></td></tr><tr><td>DPBS, without Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt;</td><td>ThermoFischer Scientific</td><td>14190094</td><td></td></tr><tr><td>Fetal bovine serum gold</td><td>GE Health Care Life Science</td><td>A15-151</td><td>FBS</td></tr><tr><td>Goniometer OCA35</td><td>Dataphysics</td><td></td><td>for the determination of the static water contact angle</td></tr><tr><td>Hoechst Dye 33342</td><td>Sigma-Aldrich</td><td>B1155-100MG</td><td>bisBenzimide H 33342 trihydrochloride, highly toxic</td></tr><tr><td>Microscope Axiovert 25</td><td>Zeiss</td><td></td><td>Microscope used for cell culture documentation</td></tr><tr><td>Microscope Eclipse LV100ND</td><td>Nikon</td><td></td><td>Microscope used for film thickness determination</td></tr><tr><td>Paraformaldehyde, aqueous solution 16%</td><td>Electron Microscopy Sciences</td><td>RT 15710</td><td>electron microscopy grade</td></tr><tr><td>penicillin und streptomycin solution</td><td>Sigma-Aldrich</td><td>P4333-100ML</td><td></td></tr><tr><td>Phenom XL Scanning Electron Microscope (SEM)</td><td>Phenom</td><td></td><td></td></tr><tr><td>Poly-(vinyl alcohol) 4-88, MW 31000</td><td>Sigma-Aldrich</td><td>81381-1KG</td><td>Mowiol 4-88</td></tr><tr><td>Poly-dimethyl siloxanes, Sylgard 184</td><td>Dow Corning</td><td>(400)000108351397</td><td>PDMS</td></tr><tr><td>RPMI 1640 basal medium</td><td>ThermoFischer Scientific</td><td>21875034</td><td></td></tr><tr><td>soft skin adhesive (SSA)</td><td>Dow Corning</td><td>(400)000108251792</td><td>MG 7-9800 Soft Skin Adhesive (SSA)</td></tr><tr><td>speed mixer DAC 600.2 VAC-P</td><td>Hauschild</td><td></td><td></td></tr><tr><td>stylus profilomter</td><td>Zeiss</td><td></td><td>Model: SURFCOM 1500SD3</td></tr><tr><td>Tecan Infinite M200 pro</td><td>Tecan</td><td></td><td>fluorescence plate reader</td></tr><tr><td>Triton X 100</td><td>Calbiochem</td><td>648466</td><td></td></tr><tr><td>Trypan Blue solution</td><td>Sigma-Aldrich</td><td>T8154-100ML</td><td>highly toxic</td></tr><tr><td>Trypsin/EDTA solution</td><td>PAN-Biotech</td><td>P10-023500</td><td>0.05% Trypsin, 0.02% EDTA in PBS</td></tr><tr><td>UV glue</td><td>Bohle</td><td>BO MV76002</td><td>medium viscosity</td></tr></tbody></table>

thin film composite silicon elastomers for cell culture and skin applications: manufacturing and characterization

In diesem Protokoll präsentieren wir Methoden, um dünne Elastomer Verbundfolien für fortgeschrittene Zelle Kultur Anwendungen und für die Entwicklung der Haut Klebstoffe zu fabrizieren. Zwei verschiedene Poly--(dimethyl siloxanes) (PDMS und weiche Haut Klebstoff (SSA)), werden seit in tiefe Untersuchung von biologischen Wirkungen und Hafteigenschaften. Die Verbundfolien bestehen aus einer flexiblen Trägerschicht und eine selbstklebende Deckschicht. Beide Schichten wurden durch Arzt Klinge Applikationstechnik hergestellt. In der vorliegenden Untersuchung ist der Klebstoffe Verhalten der Verbundfolien als Funktion der Schichtdicke oder eine Variation des Elastizitätsmoduls der obersten Ebene untersucht worden. Der Elastizitätsmodul des PDMS wurde geändert durch Variation der Ausgangspunkt, um Vernetzer Mischungsverhältnis. Darüber hinaus die Dicke der SSA Filmen variierte von ca. 16 µm bis ca. 320 µm. Scanning Electron Microscopy (SEM) und optische Mikroskopie für Dickenmessung verwendet worden. Die Hafteigenschaften der Elastomer-Filme hängen stark von der Schichtdicke, der Elastizitätsmodul von Polymeren und Oberflächeneigenschaften. Also, normale Haftung dieser Filme auf Glassubstraten mit glatten und rauen Oberflächen untersucht worden ist. Abziehen-Stress und Arbeit der Trennung sind abhängig von dem Mischungsverhältnis von Siliconelastomeren.
Außerdem variierte die Dicke der weiche Hautkleber auf eine Unterstützende Trägerschicht platziert um Patches für Haut Anwendungen zu produzieren. Zytotoxizität, Verbreitung und zelluläre Adhäsion L929 murine Fibroblasten auf PDMS Filme (Mischungsverhältnis 10:1) und SSA-Filme (Verhältnis 50: 50 mischen) wurden durchgeführt. Wir haben hier zum ersten Mal die Gegenüberstellung von zusammengesetzten Dünnfilmen beide Polymere hergestellt gezeigt und die Untersuchung ihrer biologischen und Klebstoff Eigenschaften präsentieren.

Watch this Scientific Journal Video about Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization at JoVE.com

Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

Ein Protokoll für die Herstellung von Polymeren Dünnschicht Verbundstrukturen besitzen unterschiedliche Youngs Moduli oder dicken wird vorgestellt. Filme sind für fortgeschrittene Zelle Kulturwissenschaft oder als Haut Klebstoffe hergestellt.

Dünnen Film Composite Silikon Elastomere für Zellkultur und Haut Anwendungen: Herstellung und Charakterisierung

In this protocol, we present methods to fabricate thin elastomer composite films for advanced cell culture applications and for the development of skin ...

thin-film-composite-silicon-elastomers-for-cell-culture-skin

Research

JoVE Journal

Developmental Biology

10.6K Aufrufe.  INM - Leibniz Institute for New Materials. Ein Protokoll für die Herstellung von Polymeren Dünnschicht Verbundstrukturen besitzen unterschiedliche Youngs Moduli oder dicken wird vorgestellt. Filme sind für fortgeschrittene Zelle Kulturwissenschaft oder als Haut Klebstoffe hergestellt.

Serie: Thin Film Composite Silicon Elastomers for Cell Culture and Skin Applications: Manufacturing and Characterization

Microfabricated Platforms for Mechanically Dynamic Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or fundamental cell biology studies is limited by current bioreactor technologies, which cannot simultaneously apply a variety of mechanical stimuli to cultured cells. In order to address this issue, we have developed a series of microfabricated platforms designed to screen for the effects of mechanical stimuli in a high-throughput format. In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and further demonstrate how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

In this protocol, we demonstrate the fabrication of a microactuator array of vertically displaced posts on which the technology is based, and how this base technology can be modified to conduct high-throughput mechanically dynamic cell culture in both two-dimensional and three-dimensional culture paradigms.

Mikrofabrizierten Plattformen für Mechanisch Dynamische Cell Culture

The ability to systematically probe in vitro cellular response to combinations of mechanobiological stimuli for tissue engineering, drug discovery or ...

Forschung

Biotechnik

Silk Film Culture System for in vitro Analysis and Biomaterial Design

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment 1,2 . These materials are desirable because they possess highly controllable dimensional and material characteristics, are biocompatible and promote cell adhesion, can be modified through topographic patterning or by chemically altering the surface, and can be used as a depot for biologically active molecules for drug delivery related applications 3-8 . In addition, silk films are relatively straightforward to custom design, can be designed to dissolve within minutes or degrade over years in vitro or in vivo, and are produce with the added benefit of being transparent in nature and therefore highly suitable for imaging applications 9-13. The culture system methodology presented here represents a scalable approach for rapid assessments of cell-silk film surface interactions. Of particular interest is the use of surface patterned silk films to study differences in cell proliferation and responses of cells for alignment 12,14 . The seeded cultures were cultured on both micro-patterned and flat silk film substrates, and then assessed through time-lapse phase-contrast imaging, scanning electron microscopy, and biochemical assessment of metabolic activity and nucleic acid content. In summary, the silk film in vitro culture system offers a customizable experimental setup suitable to the study of cell-surface interactions on a biomaterial substrate, which can then be optimized and then translated to in vivo models. Observations using the culture system presented here are currently being used to aid in applications ranging from basic cell interactions to medical device design, and thus are relevant to a broad range of biomedical fields.

Silk Film Culture System for in vitro Analysis and Biomaterial Design

Silk films are a novel class of biomaterials readily customizable for an array of biomedical applications. The presented silk film culture system is highly adaptable to a variety of in vitro analyses. This system represents a biomaterial design platform offering in vitro optimization before direct translation to in vivo models.

Silk Film Culture-System für In-vitro- Analyse und Design-Biomaterial

Silk films are promising protein-based biomaterials that can be fabricated with high fidelity and economically within a research laboratory environment ...

Silicon Microchips for Manipulating Cell-cell Interaction

The role of the cellular microenvironment is recognized as crucial in determining cell fate and function in virtually all mammalian tissues from development to malignant transformation.&nbsp; In particular, interaction with neighboring stroma has been implicated in a plethora of biological phenomena; however, conventional techniques limit the ability to interrogate the spatial and dynamic elements of such interactions.
In Micromechanical Reconfigurable Culture (RC), we employ a micromachined silicon substrate with moving parts to dynamically control cell-cell interactions through mechanical repositioning. Previously, this method has been applied to investigate intercellular communication in co-cultures of hepatocytes and non-parenchymal cells, demonstrating time-dependent interactions and a limited range for soluble signaling 1.
Here, we describe in detail the preparation and use of the RC system. We begin by demonstrating the handling of the device parts using tweezers, including actuating between the gap and contact configurations (cell populations separated by a narrow 80-&micro;m gap, or in direct intimate contact). Next, we detail the process of preparing the substrates for culture, and the multi-step cell seeding process required for obtaining confluent cell monolayers. Using live microscopy, we then illustrate real-time manipulation of cells between the different possible experimental configurations. Finally, we demonstrate the steps required in order to regenerate the device surface for reuse: toluene and piranha cleaning, polystyrene coating, and oxygen plasma treatment.

This article describes an experimental approach for dynamic regulation of cell-cell interactions between adherent cells on a micrometer scale. Manipulation of intercellular communication between hepatocytes and stromal cell is demonstrated. The developed platform enables investigation of cell-cell interactions in a variety of biological processes, including development and pathogenesis.

Silizium-Mikrochips zur Manipulation Zell-Zell-Interaktion

The role of the cellular microenvironment is recognized as crucial in determining cell fate and function in virtually all mammalian tissues from ...

Biologie

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

Herstellungsverfahren einer Silikonbasis Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

Ingenieurwesen

Microfabrication of Chip-sized Scaffolds for Three-dimensional Cell cultivation

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell cultivation. These technologies offer a wide spectrum of advantages not only for manufacturing but also for different applications. The size and shape of formed cell clusters can be influenced by the exact and reproducible architecture of the microfabricated scaffold and, therefore, the diffusion path length of nutrients and gases can be controlled.1 This is unquestionably a useful tool to prevent apoptosis and necrosis of cells due to an insufficient nutrient and gas supply or removal of cellular metabolites.
Our polymer chip, called CellChip, has the outer dimensions of 2 x 2 cm with a central microstructured area. This area is subdivided into an array of up to 1156 microcontainers with a typical dimension of 300 m edge length for the cubic design (cp- or cf-chip) or of 300 m diameter and depth for the round design (r-chip).2
So far, hot embossing or micro injection moulding (in combination with subsequent laborious machining of the parts) was used for the fabrication of the microstructured chips. Basically, micro injection moulding is one of the only polymer based replication techniques that, up to now, is capable for mass production of polymer microstructures.3 However, both techniques have certain unwanted limitations due to the processing of a viscous polymer melt with the generation of very thin walls or integrated through holes. In case of the CellChip, thin bottom layers are necessary to perforate the polymer and provide small pores of defined size to supply cells with culture medium e.g. by microfluidic perfusion of the containers.
In order to overcome these limitations and to reduce the manufacturing costs we have developed a new microtechnical approach on the basis of a down-scaled thermoforming process. For the manufacturing of highly porous and thin walled polymer chips, we use a combination of heavy ion irradiation, microthermoforming and track etching. In this so called "SMART" process (Substrate Modification And Replication by Thermoforming) thin polymer films are irradiated with energetic heavy projectiles of several hundred MeV introducing so-called "latent tracks" Subsequently, the film in a rubber elastic state is formed into three dimensional parts without modifying or annealing the tracks. After the forming process, selective chemical etching finally converts the tracks into cylindrical pores of adjustable diameter.

We present two processes for the microfabrication of porous polymer chips for three-dimensional cell cultivation. The first one is hot embossing combined with a solvent vapour welding process. The second one uses a recently developed microthermoforming process combined with ion track technology leading to a significant simplification of manufacture.

Microfabrication der Chip-Größe Gerüste für die dreidimensionale Kultivierung der Zellen

Using microfabrication technologies is a prerequisite to create scaffolds of reproducible geometry and constant quality for three-dimensional cell ...

Stretching Micropatterned Cells on a PDMS Membrane

Mechanical forces exerted on cells and/or tissues play a major role in numerous processes. We have developed a device to stretch cells plated on a PolyDiMethylSiloxane (PDMS) membrane, compatible with imaging. This technique is reproducible and versatile. The PDMS membrane can be micropatterned in order to confine cells or tissues to a specific geometry. The first step is to print micropatterns onto the PDMS membrane with a deep UV technique. The PDMS membrane is then mounted on a mechanical stretcher. A chamber is bound on top of the membrane with biocompatible grease to allow gliding during the stretch. The cells are seeded and allowed to spread for several hours on the micropatterns. The sample can be stretched and unstretched multiple times with the use of a micrometric screw. It takes less than a minute to apply the stretch to its full extent (around 30%). The technique presented here does not include a motorized device, which is necessary for applying repeated stretch cycles quickly and/or computer controlled stretching, but this can be implemented. Stretching of cells or tissue can be of interest for questions related to cell forces, cell response to mechanical stress or tissue morphogenesis. This video presentation will show how to avoid typical problems that might arise when doing this type of seemingly simple experiment.

This manuscript presents a technique to apply or release forces on adherent cells or tissues using unidirectional stretching.

Stretching-Cells auf einer mikrostrukturierten PDMS-Membran

Mechanical forces exerted on cells and/or tissues  play a major role in numerous processes. We have developed a device to stretch  cells plated on a ...

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application

This study discusses a synthesis route for soft polysiloxane-based urea (PSU) elastomers for their applications as accommodating intraocular lenses (a-IOLs). Aminopropyl-terminated polydimethylsiloxanes (PDMS) were previously prepared via the ring-chain equilibration of the cyclic siloxane octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). Phenyl groups were introduced into the siloxane backbone via the copolymerization of D4 and 2,4,6,8-tetramethyl-2,4,6,8-tetraphenyl-cyclotetrasiloxane (D4Me,Ph). These polydimethyl-methyl-phenyl-siloxane-block copolymers were synthesized for increasing the refractive indices of polysiloxanes. For applications as an a-IOL, the refractive index of the polysiloxanes must be equivalent to that of a young human eye lens. The polysiloxane molecular weight is controlled by the ratio of the cyclic siloxane to the endblocker APTMDS. The transparency of the PSU elastomers is examined by the transmittance measurement of films between 200 and 750 nm, using a UV-Vis spectrophotometer. Transmittance values at 750 nm (upper end of the visible spectrum) are plotted against the PDMS molecular weight, and &#62; 90% of the transmittance is observed until a molecular weight of 18,000 g&#183;mol&#8722;1. Mechanical properties of the PSU elastomers are investigated using stress-strain tests on die-cut dog-bone-shaped specimens. For evaluating mechanical stability, mechanical hysteresis is measured by repeatedly stretching (10x) the specimens to 5% and 100% elongation. Hysteresis considerably decreases with the increase in the PDMS molecular weight. In vitro cytotoxicity of some selected PSU elastomers is evaluated using an MTS cell viability assay. The methods described herein permit the synthesis of a soft, transparent, and noncytotoxic PSU elastomer with a refractive index approximately equal to that of a young human eye lens.

This study describes synthetic routes for aminopropyl-terminated polydimethylsiloxanes and polydimethyl-methyl-phenyl-siloxane-block copolymers and for soft polysiloxane-based urea (PSU) elastomers. It presents the application of PSUs as accommodating an intraocular lens. An evaluation method for in vitro cytotoxicity is also described.

Synthese von weichen Polysiloxan-Harnstoff-Elastomeren für Intraokularlinsen Anwendung

This study discusses a synthesis route for soft polysiloxane-based urea (PSU) elastomers for their applications as accommodating intraocular lenses ...

Chemie

Fabrication and Characterization of a Conformal Skin-like Electronic System for Quantitative, Cutaneous Wound Management

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of cutaneous wound healing on the skin. Existing methods, however, still rely on visual inspections through various microscopic tools and devices that normally include high-cost, sophisticated systems and require well trained personnel for operation and data analysis. Here, we describe methods and protocols to fabricate a conformal, skin-like electronics system that enables conformal lamination to the skin surface near the wound tissues, which provides recording of high fidelity electrical signals such as skin temperature and thermal conductivity. The methods of device fabrication provide details of step-by-step preparation of the microelectronic system that is completely enclosed with elastomeric silicone materials to offer electrical isolation. The experimental study presents multifunctional, biocompatible, waterproof, reusable, and flexible/stretchable characteristics of the device for clinical applications. Protocols of clinical testing provide an overview and sequential process of cleaning, testing setup, system operation, and data acquisition with the skin-like electronics, gently mounted on hypersensitive, cutaneous wound and contralateral tissues on patients.

This article presents methods to fabricate and characterize a conformal, skin-like electronic system and protocols for the use in clinical applications, particularly on cutaneous wound management.

Herstellung und Charakterisierung eines Conformal-Haut-like Electronic System for Quantitative, kutane Wundmanagement

Recent advances in the development of electronic technologies and biomedical devices offer opportunities for non-invasive, quantitative assessment of ...

Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and as soft robots. Here, we demonstrate the preparation of shape-responsive liquid crystal elastomers (LCEs) and LCE nanocomposites along with characterization of their shape-responsiveness, mechanical properties, and microstructure. Two types of LCEs &#8212; polysiloxane-based and epoxy-based &#8212; are synthesized, aligned, and characterized. Polysiloxane-based LCEs are prepared through two crosslinking steps, the second under an applied load, resulting in monodomain LCEs. Polysiloxane LCE nanocomposites are prepared through the addition of conductive carbon black nanoparticles, both throughout the bulk of the LCE and to the LCE surface. Epoxy-based LCEs are prepared through a reversible esterification reaction. Epoxy-based LCEs are aligned through the application of a uniaxial load at elevated (160 &#176;C) temperatures. Aligned LCEs and LCE nanocomposites are characterized with respect to reversible strain, mechanical stiffness, and liquid crystal ordering using a combination of imaging, two-dimensional X-ray diffraction measurements, differential scanning calorimetry, and dynamic mechanical analysis. LCEs and LCE nanocomposites can be stimulated with heat and/or electrical potential to controllably generate strains in cell culture media, and we demonstrate the application of LCEs as shape-responsive substrates for cell culture using a custom-made apparatus.

We demonstrate the preparation of siloxane-based and epoxy-based liquid crystal elastomers (LCEs) and LCE nanocomposites. The LCEs are characterized with respect to reversible strain, liquid crystal ordering, and stiffness. As a potential application, we demonstrate their use as shape-responsive substrates in a custom device for active cell culture.

Herstellung von Monodomäne Liquid Crystal Elastomere und Liquid Crystal Elastomer Nanokomposite

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and ...

A Simple and Scalable Fabrication Method for Organic Electronic Devices on Textiles

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices cannot be worn under everyday conditions. Therefore, textiles are commonly considered the best substrate to accommodate electronic devices in wearable use. In this paper, we describe how to selectively pattern organic electroactive materials on textiles from a solution in an easy and scalable manner. This versatile deposition technique enables the fabrication of wearable organic electronic devices on clothes.

In this paper, we present a protocol to selectively deposit organic materials on textiles, which allows for the direct integration of organic electronic devices with wearables. The fabricated devices can be fully integrated in textiles, respecting their mechanical appearance and enabling sensing capabilities.

Eine einfache und skalierbare Herstellungsverfahren für organische elektronische Vorrichtungen auf Textilien

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices ...