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Inspired by the dynamic process of initial bone development, in which a soft tissue turns into a solid load-bearing structure, the fabrication, optimization, and characterization of bioinduced variable-stiffness actuators that can morph in various shapes and change their properties from soft to rigid are hereby presented. Bilayer devices are prepared by combining the electromechanically active properties of polypyrrole with the compliant behavior of alginate gels that are uniquely functionalized with cell-derived plasma membrane nanofragments (PMNFs), previously shown to mineralize within 2 days, which promotes the mineralization in the gel layer to achieve the soft to stiff change by growing their own bone. The mineralized actuator shows an evident frozen state compared to the movement before mineralization. Next, patterned devices show programmed directional and fixated morphing. These variable-stiffness devices can wrap around and, after the PMNF-induced mineralization in and on the gel layer, adhere and integrate onto bone tissue. The developed biohybrid variable-stiffness actuators can be used in soft (micro-)robotics and as potential tools for bone repair or bone tissue engineering. Funding Agencies: Japanese Society of the Promotion of Science (JSPS) Bridge Fellowship program [BR170502]; KAKENHI Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) [JP20H04534]; Swedish Research Council European Commission [VR2014-3079]; Promobilia [F17603]; China Scholarship Council [201808330454]; JSPS Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science [JPJSBP 120 209 923]; STINT, The Swedish Foundation for International Cooperation in Research and Higher Education [MG2019-8171]

To control and manipulate fluids in lab‐on‐a‐chip (LOC) devices, active components such as pumps, valves, and injectors are necessary. However, such components are often complex and expensive to fabricate, limiting integration in disposable LOCs. A new type of flexible, all‐polymer diaphragm actuator system, called Double Diaphragm Active Polymer Actuator (DDAPA), is presented as a single modular unit that can be repurposed to diverse active microfluidic components. To demonstrate the versatility of the DDAPA concept, the DDAPA devices are investigated in three different configurations: as a single operation microinjector, as a flow regulating element, and as a pump in a hybrid configuration with unibody‐LOC unidirectional systems. The working principle, fabrication process, and the three examples of microfluidic components are presented. The trilayer diaphragm actuator is realized using the conductive polymer poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate as the actuating material and thiol‐acrylate‐based ionogels as solid‐state electrolyte and base material. The three demonstrators show the feasibility of using the DDAPA module to inject liquids, regulate flow, and unidirectionally pump fluids up to 112 µL min−1 when coupled with a 3D printed unibody check valve. Hence, the presented concept with a simple mechanism and easy manufacturability, broadens the choice of disposable actuators compatible with fully disposable autonomous LOC solutions. Funding agencies:The research was supported by European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska Curie grant agreement No. 641822, Swedish Research Council (VR-2014-3079), and Familjen Erling-Perssons Stiftelse.

Textiles are ubiquitous materials and no man-made class of material offers such a proximity to the body and as such ever-presence in human life as textiles. Part of this is due to textiles having the rather unique property of drapability and pliability which is used in clothing. Soft actuators are flexible and typically lightweight and silent and are, therefore, well suited to be integrated in fabrics and textiles, resulting in textile actuators for wearables such as exoskeletons. In this chapter, we address various yarn and fabric actuators and describe two examples of textile actuators, thermal-driven textile actuators, and electrochemical textile actuators, in more detail.

Nonconductive commercial viscose yarns have been coated with a commercial conducting poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) layer providing electrical conductivity which allowed a second coating of the electroactive conducting polymer polypyrrole through electropolymerization to develop textile yarns actuators. To simplify the PEDOT coating process and at the same time make this process more suitable for application in industry, a new coating method is developed and the properties of the PEDOT-PSS conducting layer is optimized, paying attention on its effect on the actuation performance. The effect of the concentration of an additive such as dimethylsulfoxide (DMSO) on actuation, and of PEDOT:PSS layers, is investigated. Results show that on improving this conducting layer, better performance than previously developed yarn-actuators is obtained, with strains up to 0.6%. This study provides a simple and efficient fabrication method toward soft, textile-based actuators for wearables and assistive devices with improved features. Funding agencies: The authors acknowledge the Erling-Persson Family Foundation,Promobilia Foundation (F17603), Union’s Horizon 2020 research andinnovation program under grant agreement no. 825232 “WEAFING”for their nancial support. E.W.H.J. acknowledges nancial support fromthe Swedish Government Strategic Research Area in Materials Science onFunctional Materials at Linköping University (Faculty Grant SFO Mat LiUNo. 2009 00971). F.E-T. acknowledges Universidad Tecnica de Ambato(UTA-FCIAL-UODIDE-2018-0047-M) for the financial support.

Electrochemically or electrothermally driven twisted/coiled carbon nanotube (CNT) yarn actuators are interesting artificial muscles for wearables as they can sustain high stress. However, due to high fabrication costs, these yarns have limited their application in smart textiles. An alternative approach is to use off-the-shelf yarns and coat them with conductive polymers that deliver high actuation properties. Here, novel hybrid textile yarns are demonstrated that combine CNT and an electroactive polypyrrole coating to provide both high strength and good actuation properties. CNT-coated polyester yarns are twisted and coiled and subjected to electrochemical coating of polypyrrole to obtain the hierarchical soft actuators. When twisted without coiling, the polypyrrole-coated yarns produce fully reversible 25 degrees mm(-1)rotation, 8.3x higher than the non-reversible rotation from twisted CNT-coated yarns in a three-electrode electrochemical system operated between +0.4 and -1.0 V (vs Ag/AgCl). The coiled yarns generate fully reversible 10 degrees mm(-1)rotation and 0.22% contraction strain, 2.75x higher than coiled CNT-coated yarns, when operated within the same potential window. The twisted and coiled yarns exhibit high tensile strength with excellent abrasion resistance in wet and dry shearing conditions that can match the requirements for using them as soft actuators in wearables and textile exoskeletons. Funding Agencies|Promobilia Foundation [F17603]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (faculty grant SFO Mat LiU) [2009-00971]; Swedish Research CouncilSwedish Research Council [2014-3079]; Carl Trygger Foundation [CTS:17-215]; European Unions Horizon 2020 research and innovation program [825232]; University of Wollongongs Visiting International Scholar Award

Commercially available yarns are promising precursor for artificial muscles for smart fabric-based textile wearables. Electrochemically driven conductive polymer (CP) coated yarns have already shown their potential to be used in smart fabrics. Unfortunately, the practical application of these yarns is still hindered due to their slow ion exchange properties and low strain. Here, a method is demonstrated to morph poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS) coated multifilament textile yarns in highly twisted and coiled structures, providing >1% linear actuation in 1.62% strain. Compared to the untwisted, regular yarns, the twisted and coiled yarns produce >9x and >20x higher strain, respectively. The strain and speed are significantly higher than the maximum reported results from other electrochemically operated CP yarns. The yarns actuation is explained by reversible oxidation/reduction reactions occurring at CPs. However, the helical opening/closing of the twisted or coiled yarns due to the torsional yarn untwisting/retwisting assists the rapid and large linear actuation. These PEDOT:PSS coated yarn actuators are of great interest to drive smart textile exoskeletons. Funding Agencies|Promobilia Foundation [F17603]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009-00971]; Swedish Research CouncilSwedish Research Council [2014-3079]; Carl Trygger Foundation [CTS:17-215]; European UnionEuropean Union (EU) [825232]; University of Wollongongs Visiting International Scholar Award

Untethered actuation is important for robotic devices to achieve autonomous motion, which is typically enabled by using batteries. Using enzymes to provide the required electrical charge is particularly interesting as it will enable direct harvesting of fuel components from a surrounding fluid. Here, a soft artificial muscle is presented, which uses the biofuel glucose in the presence of oxygen. Glucose oxidase and laccase enzymes integrated in the actuator catalytically convert glucose and oxygen into electrical power that in turn is converted into movement by the electroactive polymer polypyrrole causing the actuator to bend. The integrated bioelectrode pair shows a maximum open-circuit voltage of 0.70 +/- 0.04 V at room temperature and a maximum power density of 0.27 mu W cm(-2) at 0.50 V, sufficient to drive an external polypyrrole-based trilayer artificial muscle. Next, the enzymes are fully integrated into the artificial muscle, resulting in an autonomously powered actuator that can bend reversibly in both directions driven by glucose and O-2 only. This autonomously powered artificial muscle can be of great interest for soft (micro-)robotics and implantable or ingestible medical devices manoeuvring throughout the body, for devices in regenerative medicine, wearables, and environmental monitoring devices operating autonomously in aqueous environments. Funding Agencies|EU Marie Curie Actions Initial Training Network MICACTEuropean Union (EU) [641822]; Swedish Research CouncilSwedish Research Council [2014-3079]; Carl Trygger Foundation [CTS16:207]; Carl Tryggers Stiftelse [CTS16:207]

A simple and cost-effective method for the patterning and fabrication of soft polymer microactuators integrated with morphological computation is presented. The microactuators combine conducting polymers to provide the actuation, with spatially designed structures for a morphologically controlled, user-defined actuation. Soft lithography is employed to pattern and fabricate polydimethylsiloxane layers with geometrical pattern, for use as a construction element in the microactuators. These microactuators could obtain multiple bending motions from a single fabrication process depending on the morphological pattern defined in the final step. Instead of fabricating via conventional photolithography route, which involves multiple steps with different chromium photomasks, this new method uses only one single design template to produce geometrically patterned layers, which are then specifically cut to obtain multiple device designs. The desired design of the actuator is decided in the final step of fabrication. The resulting microactuators generate motions such as a spiral, screw, and tube, using a single design template., Microrobots: Novel fabrication of artificial muscle A novel technique can fabricate multiple ‘soft microrobots’ from a single design process that may prove useful in biomedical applications. With a continuous drive for robots to get smaller and more efficient, researchers are looking for alternatives to complex, traditional machinery. Edwin Jager and his team from Linköping University in Sweden now report a technique that combines elastomeric silicone and electroactive polymer into an artificial muscle: a soft microrobot actuated depending on the presence of ions in solution. Through controlling the thickness and length of rigid and flexible sections, the team’s devices can produce multiple, different motions such as spiraling and screwing. Such soft robots could find uses in future minimally invasive surgery or drug delivery systems. Jager and his team are now working on soft robots that function in air.

The combination of stem cell therapy with a supportive scaffold is a promising approach to improving cardiac tissue engineering. Stem cell therapy can be used to repair nonfunctioning heart tissue and achieve myocardial regeneration, and scaffold materials can be utilized in order to successfully deliver and support stem cells in vivo. Current research describes passive scaffold materials; here an electroactive scaffold that provides electrical, mechanical, and topographical cues to induced human pluripotent stem cells (iPS) is presented. The poly(lactic-co-glycolic acid) fiber scaffold coated with conductive polymer polypyrrole (PPy) is capable of delivering direct electrical and mechanical stimulation to the iPS. The electroactive scaffolds demonstrate no cytotoxic effects on the iPS as well as an increased expression of cardiac markers for both stimulated and unstimulated protocols. This study demonstrates the first application of PPy as a supportive electroactive material for iPS and the first development of a fiber scaffold capable of dynamic mechanical actuation. Funding Agencies|Linkoping University, Integrative Regenerative Medicine (IGEN) Center; Swedish Research Council [VR-2014-3079]; COST-Action [MP1003]; Knut och Alice Wallenberg Commemorative Fund; GeCONiI [POIG.02.03.01-24-099/13]; European Research Agency

Tuning the physical–chemical properties of polypyrrole (PPy) opens up potentially exciting new applications, especially in the area of bacterial adhesion. Polypyrrole is electrochemically synthesized under various conditions and the physical properties of the films and their effects on bacterial adhesion are characterized. Five types of dopants—chloride (Cl), perchlorate (ClO4), p-toluene-sulfonate (ToS), dodecylbenzene sulfonate (DBS), and poly sodium styrene sulfonate (PSS)—are used to fabricate PPy films at two different constant potentials (0.500 and 0.850 V) with and without Fe3+. Their thickness, roughness, and wettability are measured. The adhesion tendency of Escherichia coli, as a model bacterium, to the four polymers is studied. E. coli shows greater adhesion tendency to the hydrophobic, rough surface of PPy-DBS, and less adhesion tendency to the smooth and hydrophilic surface of PPy-PSS. The results facilitate the choice of appropriate electropolymerization conditions to modulate bacterial adhesion. Funding agencies: Iranian Ministry of Science, Research and Technology; Linkoping University; Swedish Research Council [VR-2014-3079]

Hierarchically structured materials (HSMs) are becoming increasingly important in catalysis, separation and energy applications due to their advantageous diffusion and flux properties. Here, we introduce a facile modular approach to fabricate HSMs with tailored functional conducting polypyrrole microparticles (PPyMP). The PPyMPs were fabricated with a calcium carbonate (CaCO3) template-assisted polymerization technique in aqueous media at room temperature, thus providing a new green chemistry for producing water-processable functional polymers. The sacrificial CaCO3 template guided the polymerization process to yield homogenous PPyMPs with a narrow size distribution. The porous nature of the CaCO3 further allows the incorporation of various organic and inorganic dopants such as an electrocatalyst and redox mediator for the fabrication of functional PPyMPs. Dawson-type polyoxometalate (POM) and methylene blue (MB) were chosen as the model electrocatalyst and electron mediator dopant, respectively. Hierarchically structured electrochemical interfaces were created simply by self-assembly of the functional PPyMPs. We demonstrate the versatility of this technique by creating two different hierarchical structured electrochemical interfaces: POM-PPyMPs for hydrogen peroxide electrocatalysis and MB-PPyMPs for mediated bioelectrocatalysis. We envision that the presented design concept could be extended to different conducting polymers doped with other functional organic and inorganic dopants to develop advanced electrochemical interfaces and to create high surface area electrodes for energy storage.

A novel rapid method for bacterial differentiation is explored based on the specific adhesion pattern of bacterial strains to tunable polymer surfaces. Different types of counter ions were used to electrochemically fabricate dissimilar polypyrrole (PPy) films with diverse physicochemical properties such as hydrophobicity, thickness and roughness. These were then modulated into three different oxidation states in each case. The dissimilar sets of conducting polymers were exposed to five different bacterial strains, Deinococcus proteolyticus, Serratia marcescens, Pseudomonas fluorescens, Alcaligenes faecalis and Staphylococcus epidermidis. By analysis of the fluorescent microscope images, the number of bacterial cells adhered to each surface were evaluated. Generally, the number of cells of a particular bacterial strain that adhered varied when exposed to dissimilar polymer surfaces, due to the effects of the surface properties of the polymer on bacterial attachment. Similarly, the number of cells that adhered varied with different bacterial strains exposed to the same surface, reflecting the different surface properties of the bacteria. Principal component analysis showed that each strain of bacteria had its own specific adhesion pattern. Hence, they could be discriminated by this simple, label-free method based on tunable polymer arrays combined with pattern recognition. (C) 2015 Elsevier B.V. All rights reserved. Funding Agencies|Iranian Ministry of Science, Research and Technology; Linkoping University; Swedish Research Council [VR-2014-3079]

Conducting polymer (CP) based soft actuators are good candidates for miniaturised manipulation systems and soft robotic applications. We present the fabrication, characterization, and modelling, of a novel ionically driven soft, flat, parallel manipulator with minimal footprint actuated by CP actuators. This three degrees of freedom (3Dof) manipulator consists of four trilayer actuators with poly (3, 4- ethylenedioxy-thiophene):poly(styrene sulfonate) (PEDOT:PSS) electrodes on both sides of PVDF separator membrane with 1-Ethyl-3-methylimidazoliummethyl imidazolium bis(trifluoromethylsulfonyl)imide ionic liquid used as the electrolyte. The complete manipulator is fabricated as a monolithic structure using commercially available off the shelf materials by additive manufacturing technique including a syringe type printer. Its workspace and dynamics are characterised and the results are compared with a multiphysics model based on the finite element method. The model uses two types of charge storage mechanism namely electrical double layer and redox reactions to describe the electrode kinetics. Through simulation the charge contributed by each of the processes is separated and presented providing new insights in the underlying kinetics in this type of actuators. It is found the double layer charge is the dominant phenomenon driving these actuators compared to the redox process. Finally, to demonstrate the versatile applications, the manipulator is explored for a four-way laser steering application. This work has demonstrated high levels of manipulability along three degrees of freedom from the printed CP actuators that are outstanding within the class of soft ionic actuators while using off the shelf commercially available materials keeping the fabrication method simple, scalable and cost-effective along with the electro-chemo-mechanical model providing an insightful view of the charge storage mechanism. Funding Agencies|European Unions Horizon 2020 research and innovation program under the Marie Sklodowska Curie grant [641822]; Estonian Research Council, Linkoping University [IUT20-24]; Swedish Research CouncilSwedish Research Council [VR-2014-3079]; Promobilia Stiftelsen [F17603]

In the original published article, the author list did not include Karl Svennersten, Kristin Persson, Edwin Jager and Magnus Berggren. After publication, we were notified by the corresponding author that the author list did not accurately reflect the contributions made, and these authors have been added to the author list. The original “Author Contributions” stated that “S.G.C., M.R., and A.R.D. designed research; S.G.C. performed all experiments…” this has been updated to read “S.G.C., K.S., K.M.P., E.W.H.J., M.B., M.R., and A.R.D. designed research; K.S., K.M.P., and E.W.H.J. performed experiments; S.G.C. performed all reported experiments…”. The “Acknowledgements” previously read “We thank K. Svennersten, A. Kader, K. Persson, and M. Berggren for fruitful discussions, and S. Löffler for insightful comments on the manuscript…” and have been updated to state “We thank A. Kader for fruitful discussions and S. Loffler for insightful comments on the manuscript…”. The “Competing Interests” section did not require any amendments. All authors have agreed with this correction statement and authorship change.

An ionic conducting membrane is an essential part in various electrochemical devices including ionic actuators. To miniaturize these devices, micropatterns of ionic conducting membrane are desired. Here, we present a novel type of ionogel that can be patterned using standard photolithography and soft imprinting lithography. The ionogel is prepared in situ by UV-initiated free-radical polymerization of thiol acrylate precursors in the presence of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The resultant ionogel is very flexible with a low Youngs modulus (as low as 0.23 MPa) and shows a very high ionic conductivity (up to 2.4 X 10(-3) S/cm with 75 wt % ionic liquid incorporated) and has a reactive surface due to the excess thiol groups. Micropatterns of ionogel are obtained by using the thiol acrylate ionogel solution as an ionic conducting photoresist with standard photolithography. Water, a solvent immiscible with ionic liquid, is used as the photoresist developer to avoid complete removal of ionic liquid from thin micropatterns of the ionogel. By taking advantage of the reactive surface of ionogels and the photopatternability, ionogels with complex three-dimensional microstructure are developed. The surface of the ionogels can also be easily patterned using UV-assisted soft imprinting lithography. This new type of ionogels may open up for building high-performance flexible electrochemical microdevices. Funding Agencies|European Unions Horizon 2020 research and innovation program under the Marie Sklodowska Curie grant [641822]; Swedish Research Council [VR-2014-3079]

Smart textiles have been around for some decades. Even if interactivity is central to most definitions, the emphasis so far has been on the stimuli/input side, comparatively little has been reported on the responsive/output part. This study discusses the actuating, mechanical, output side in what could be called a second generation of smart textiles-this in contrast to a first generation of smart textiles devoted to sensorics. This mini review looks at recent progress within the area of soft actuators and what from there that is of relevance for smart textiles. It is found that typically still forces exerted are small, so are strains for many of the actuators types (such as electroactive polymers) that could be considered for textile integration. On the other side, it is argued that for many classes of soft actuators-and, in the extension, soft robotics-textiles could play an important role. The potential of weaving for stress and knitting for strain amplification is shown. Textile processing enables effective production, as is analyzed. Textile systems are made showing automatic actuation asked for in stand-alone solutions. It is envisioned that soft exoskeletons could be an achievable goal for this second generation of smart textiles. Funding Agencies|Carl Trygger Foundation [CTS 12: 206]; Swedish Research Council [VR-2014-3079]; Smart Textiles Initiative, University of Boras

The capacity to store urine and initiate voiding is a valued characteristic of the human urinary bladder. To maintain this feature, it is necessary that the bladder can sense when it is full and when it is time to void. The bladder has a specialized epithelium called urothelium that is believed to be important for its sensory function. It has been suggested that autocrine ATP signalling contributes to this sensory function of the urothelium. There is well‐established evidence that ATP is released via vesicular exocytosis as well as by pannexin hemichannels upon mechanical stimulation. However, there are still many details that need elucidation and therefore there is a need for the development of new tools to further explore this fascinating field. In this work, we use new microphysiological systems to study mechanostimulation at a cellular level: a mechanostimulation microchip and a silicone‐based cell stretcher. Using these tools, we show that ATP is released upon cell stretching and that extracellular ATP contributes to a major part of Ca2+ signalling induced by stretching in T24 cells. These results contribute to the increasing body of evidence for ATP signalling as an important component for the sensory function of urothelial cells. This encourages the development of drugs targeting P2 receptors to relieve suffering from overactive bladder disorder and incontinence.

There is a need for soft actuators in various biomedical applications in order to manipulate delicate objects such as cells and tissues. Soft actuators are able to adapt to any shape and limit the stress applied to delicate objects. Conjugated polymer actuators, especially in the so-called trilayer configuration, are interesting candidates for driving such micromanipulators. However, challenges involved in patterning the electrodes in a trilayer with individual contact have prevented further development of soft micromanipulators based on conjugated polymer actuators. To allow such patterning, two printing-based patterning techniques have been developed. First an oxidant layer is printed using either syringe-based printing or micro-contact printing, followed by vapor phase polymerization of the conjugated polymer. Sub-millimeter patterns with electronic conductivities of 800 Scm-1 are obtained. Next, laser ablation is used to cleanly cut the final device structures including the printed patterns, resulting in fingers with individually controllable digits and miniaturized hands. The methods presented in this paper will enable integration of patterned electrically active conjugated polymer layers in many types of complex 3-D structures. Funding agencies:This study was financially supported by Linköping University, COST Action MP1003 ESNAM (European Scientific Network for Artificial Muscles), the Swedish Research Council (VR – 2010-6672, 2014-3079, 2015-03298), the Knut & Alice Wallenberg Stiftelse (LiU-2010-00318 & LiU-2012- 01361), and the EU FP7 Marie Curie action IEF (625923 POLYACT)

Hematopoietic stem cells are used in transplantations for patients with hematologic malignancies. Scarce sources require efficient strategies of expansion, including polymeric biomaterials mimicking architectures of bone marrow tissue. Tissue microenvironment and mode of cytokine presentation strongly influence cell fate. Although several cytokines with different functions as soluble or membrane-bound mediators have already been identified, their precise roles have not yet been clarified. A need exists for in vitro systems that mimic the in vivo situation to enable such studies. One way is to establish surfaces mimicking physiological presentation using protein-immobilization onto polymer films. However these films merely provide a static presentation of the immobilized proteins. It would be advantageous to also dynamically change protein presentation and functionality to better reflect the in vivo conditions. The electroactive polymer polypyrrole shows excellent biocompatibility and electrochemically alters its surface properties, becoming an interesting choice for such setups. Here, we present an in vitro system for switchable presentation of membrane-bound cytokines. We use interleukin IL-3, known to affect hematopoiesis, and show that when immobilized on polypyrrole films, IL-3 is bioavailable for the bone marrow-derived FDC-P1 progenitor cell line. Moreover, IL-3 presentation can be successfully altered by changing the redox state of the film, in turn influencing FDC-P1 cell viability. This novel in vitro system provides a valuable tool for stimuli-responsive switchable protein presentation allowing the dissection of relevant mediators in stem and progenitor cell behavior.

A ternary composite supercapacitor electrode consisting of phosphomolybdic acid (HMA), a renewable biopolymer, lignin, and polypyrrole was synthesized by a simple one-step simultaneous electrochemical deposition and characterized by electrochemical methods. It was found that the addition of HMA increased the specific capacitance of the polypyrrole–lignin composite from 477 to 682 F g−1 (at a discharge current of 1 A g−1) and also significantly improved the charge storage capacity from 69 to 128 mA h g−1.

Electrically-active nanoporous membranes are prepared by coating the surface of anodized alumina with electroactive polymers using vapor phase polymerization with four combinations of conjugated po ...

Conducting polymer actuators such as polypyrrole (PPy) microactuators are interesting candidates to drive autonomous microrobotic devices that require low weight and low power. Simple PPy tri-layer bending type microactuators that operate in air have been demonstrated previously but they lack individual control and had problems with short circuiting due to electrical connections. The lack of micropatterning methods and proper interfacing are currently major obstacles in the development of PPy tri-layer microactuators. Here, we report for the first time methods for successfully patterning and interfacing of such tri-layer PPy microactuators. The PPy tri-layer actuators were patterned using adapted microfabrication technology including photolithography. The interface was based on a flexible printed circuit board comprising the electronic circuit into which the actuator unit was embedded. It showed that the microfabricated tri-layer actuators functioned as good as the normally fabricated actuators. The new interface seemed to actually improve the actuator performance. This interfacing method could also be applied to other electroactive polymer devices, such as ion polymer metal composites (IPMC) and dielectric elastomers (DE).

Biosensors can deliver the rapid bacterial detection that is needed in many fields including food safety, clinical diagnostics, biosafety and biosecurity. Whole-cell imprinted polymers have the potential to be applied as recognition elements in biosensors for selective bacterial detection. In this paper, we report on the use of 3-aminophenylboronic acid (3-APBA) for the electrochemical fabrication of a cell-imprinted polymer (CIP). The use of a monomer bearing a boronic acid group, with its ability to specifically interact with cis-diol, allowed the formation of a polymeric network presenting both morphological and chemical recognition abilities. A particularly beneficial feature of the proposed approach is the reversibility of the cis-diol-boronic group complex, which facilitates easy release of the captured bacterial cells and subsequent regeneration of the CIP. Staphylococcus epidermidis was used as the model target bacteria for the CIP and electrochemical impedance spectroscopy (EIS) was explored for the label-free detection of the target bacteria. The modified electrodes showed a linear response over the range of 103–107 cfu/mL. A selectivity study also showed that the CIP could discriminate its target from non-target bacteria having similar shape. The CIPs had high affinity and specificity for bacterial detection and provided a switchable interface for easy removal of bacterial cell. Funding agencies: Ministry of Science Research and Technology of Iran [MSRT 89100094]; Linkoping University [1259 00 0200]; Swedish Research Council [VR-2014-3079]

Cellular mechanotransduction is crucial for physiological function in the lower urinary tract. The bladder is highly dependent on the ability to sense and process mechanical inputs, illustrated by the regulated filling and voiding of the bladder. However, the mechanisms by which the bladder integrates mechanical inputs, such as intravesicular pressure, and controls the smooth muscles, remain unknown. To date no tools exist that satisfactorily mimic in vitro the dynamic micromechanical events initiated e.g. by an emerging inflammatory process or a growing tumour mass in the urinary tract. More specifically, there is a need for tools to study these events on a single cell level or in a small population of cells. We have developed a micromechanical stimulation chip that can apply physiologically relevant mechanical stimuli to single cells to study mechanosensitive cells in the urinary tract. The chips comprise arrays of microactuators based on the electroactive polymer polypyrrole (PPy). PPy offers unique possibilities and is a good candidate to provide such physiological mechanical stimulation, since it is driven at low voltages, is biocompatible, and can be microfabricated. The PPy microactuators can provide mechanical stimulation at different strains and/or strain rates to single cells or clusters of cells, including controls, all integrated on one single chip, without the need to preprepare the cells. This paper reports initial results on the mechano-response of urothelial cells using the micromechanical stimulation chips. We show that urothelial cells are viable on our microdevices and do respond with intracellular Ca2+ increase when subjected to a micro-mechanical stimulation.

Artificial muscles are the longtime dream of human being to replace the existing engines, motors, and piezoelectric actuators because of the low-noise, environment-friendly, and energy-saving actua ...

Conjugated polymer actuators are devices where the volume of a conjugated (or conducting) polymer material is changed during a change of the state of oxidation or reduction of the polymer. This volume change can be utilized to construct actuators, for instance as a single layer or fiber resulting in a linear actuator or assembled into a multilayer structure where the active material is combined with a passive supporting material forming bending actuator.

Handling of soft and fragile sub-millimeter sized samples such as cells and tissues requires new tools that allow delicate manipulation. Conducting polymer actuators show unique characteristics suitable to driving such manipulators, however despite their potential, the current fabrication method of the trilayer structures does not allow constructing advanced micromanipulators operating in air using this technology. Here we show a novel bottom-up microfabrication process for conjugated polymer trilayer actuators using various solid polymer electrolytes. In addition, the process design integrates contact pads, which has been an issue for small scale conducting polymer actuators. The microfabrication process starts with a patterned layer of conjugated polymer, followed by depositing a polymer electrolyte and a second patterning of the second conjugated polymer layer. The process resulted in successful fabrication of individually controllable conducting polymer trilayer actuators comprising polyvinylidenefluoride and poly( vinylidenefluoride-co-hexafluoropropylene) membranes and showed good interfacial adhesion between the different layers in the final device. The polyvinylidenefluoride trilayer actuator showed good actuation capability. The developed bottom-up microfabrication method paves the way for the development of novel micromanipulation tools. (C) 2016 Elsevier B.V. All rights reserved. Funding Agencies|Linkoping University; EU FP7 Marie Curie action IEF [625923]; COST Action ESNAM (European Scientific Network for Artificial Muscles) [MP1003]; Swedish Research Council [VR-2010-6672, VR-2014-3079]; Knut & Alice Wallenberg Stiftelse [LiU-2010-00318, LiU-2012-01361, LiU-2014-01752]; Australian Research Council [CE14010012, DP110101073]; [COST-STSM-MP1003-8971]; [COST-STSM-MP1003-13878]; [COST-STSM-MP1003-16675]

This chapter focuses on device configurations based on conjugated polymer transducers. After the actuation and sensing configurations in the literature are presented, some successful device configu ...

The characterisation of biomaterials for cardiac tissue engineering applications is vital for the development of effective treatments for the repair of cardiac function. New smart materials developed from conductive polymers can provide dynamic benefits in supporting and stimulating stem cells via controlled surface properties, electrical and electromechanical stimulation. In this study we investigate the control of surface properties of conductive polymers through a systematic approach to variable synthesis parameters, and how the resulting surface properties influence the viability of cardiac progenitor cells. A thorough analysis investigating the effect of electropolymerisation parameters, such as current density and growth, and reagent variation on physical properties provides a fundamental understanding of how to optimise conductive polymer biomaterials for cardiac progenitor cells. Funding Agencies|Linkoping University; IGEN (post-doc grant); COST-Action [MP1003]; Knut och Alice Wallenberg Commemorative Fund; European Research Agency

In this chapter, first some basic principles of photolithography and general microfabrication are introduced. These methods have been adapted to fit the microfabrication of conducting polymer actua ...

Polypyrrole coated gold wires were subjected to consecutive square current waves in LiClO4 aqueous solutions using the same constant anodic and cathodic charge. Parallel in situ diameter variations were followed using a laser scan micrometer. The procedure was repeated by changing one experimental variable every time: applied current, electrolyte concentration or working temperature to perform electrochemodynamical characterization of the system. On average, the diameter follows a linear variation of the consumed charge, as expected for any faradaic system, although a high dispersion was attained in the data. Such deviations were attributed to the presence of irreversible hydrogen evolution at the gold/polypyrrole interface at cathodic potentials more than 0.0 V vs. Ag/AgCl, detected and quantified from separated coulovoltammetric responses. Despite this parallel hydrogen evolution the consumed energy during reactions is a robust sensor of the working conditions. In conclusion a gold support, the metal most used for technological applications of conducting polymers, should be avoided when a device is driven by current flow in the presence of aqueous solutions, water contamination or moisture: a fraction of the charge will be consumed by hydrogen generation with possible degradation of the device. Funding Agencies|Spanish Government (MCINN) [MAT2011-24973]; Seneca Foundation [19253/PI/14]; European Science Foundation COST Action European Scientific Network for Artificial Muscles (ESNAM) [COST-STSM-MP1003-11575, COST-STSM-MP1003-11581, MP1003]; Swedish Research Council [VR-2014-3079]; Linkoping University; Spanish Education Ministry [AP2010-3460]

A flexible electronic paper in full color is realized by plasmonic metasurfaces with conjugated polymers. An ultrathin large-area electrochromic material is presented which provides high polarization-independent reflection, strong contrast, fast response time, and long-term stability. This technology opens up for new electronic readers and posters with ultralow power consumption. Funding Agencies|Swedish Foundation for Strategic Research; Chalmers Nanoscience and Nanotechnology Area of Advance

The Gram-negative bacterium, Salmonella Typhimurium (S. Typhimurium) is a food borne pathogen responsible for numerous hospitalisations and deaths all over the world. Conventional detection methods for pathogens are time consuming and labour-intensive. Hence, there is considerable interest in faster and simpler detection methods. Polypyrrole-based polymers, due to their intrinsic chemical and electrical properties, have been demonstrated to be valuable candidates for the fabrication of chemo/biosensors and functional surfaces. Similarly aptamers have been shown to be good alternatives to antibodies in the development of affinity biosensors. In this study, we report on the combination of Poly [pyrrole-co-3-carboxyl-pyrrole] copolymer and aptamer for the development of a label-less electrochemical biosensor suitable for the detection of S. Typhimurium. Impedimetric measurements were facilitated by the effect of the aptamer/target interaction on the intrinsic conjugation of the poly [pyrrole-co-3-carboxyl-pyrrole] copolymer and subsequently on its electrical properties. The aptasensor detected S. Typhimurium in the concentration range 10(2)-10(8) CFU mL(-1) with high selectivity over other model pathogens and with a limit of quantification (LOQ) of 100 CFU mL(-1) and a limit of detection (LOD) of 3 CFU mL(-1). The suitability of the aptasensor for real sample detection was demonstrated via recovery studies performed in spiked apple juice samples. We envisage this to be a viable approach for the inexpensive and rapid detection of pathogens in food, and possibly in other environmental samples. (C) 2016 Elsevier B.V. All rights reserved. Funding Agencies|Ministry of Science Research and Technology of Iran; Research Council of Ferdowsi University of Mashhad [3/29828]; Linkoping University, Vetenskapsradet [D0675001]; Swedish Research Council [VR-2014-3079]

This chapter outlines the various methods that have been developed in the past three decades to characterize the electroactive performance of conducting polymers (CP) to provide fundamental metrics ...

An electronic detachment technology based on thin films of a poly(3,4-ethylene-dioxythiophene) derivative is evaluated for controlled release of human epithelial cells. When applying a potential of 1 V, the redox-responsive polymer films detach and disintegrate and at the same time release cells cultured on top in the absence of any enzymatic treatment with excellent preservation of membrane proteins and cell viability.

Book review: Biosensors: Essentials, by Gennady Evtugyn (Lecture Notes in Chemistry Vol.84), 265 pages, Springer, 2014, ISBN 978-3-642–40240-1 Hardcover − 124,79 €; Softcover 106,90 €; eBook 86,86 €

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Complex patterning of the extracellular matrix, cells, and tissues under in situ electronic control is the aim of the technique presented here. The distribution of epithelial cells along the channel of an organic electrochemical transistor is shown to be actively controlled by the gate and drain voltages, as electrochemical gradients are formed along the transistor channel when the device is biased..

Electronically conductive and electrochemically active 3D-scaffolds based on electrospun poly(ethylene terephthalate) (PET) nano-fibers are reported. Vapour phase polymerization was employed to achieve an uniform and conformal coating of poly(3,4-ethylenedioxythiophene) doped with tosylate (PEDOT:tosylate) on the nano-fibers. The PEDOT coatings had a large impact on the wettability, turning the hydrophobic PET fibers super-hydrophilic. SH-SY5Y neuroblastoma cells were grown on the PEDOT coated fibers. The SH-SY5Y cells adhered well and showed healthy morphology. These electrically active scaffolds were used to induce Ca2+ signalling in SH-SY5Y neuroblastoma cells. PEDOT:tosylate coated nano-fibers represent a class of 3D host environments that combines excellent adhesion and proliferation for neuronal cells with the possibility to regulate their signalling. Original Publication:Maria Bolin, Karl Svennersten, Xiangjun Wang, Ioannis S Chronakis, Agneta Richter-Dahlfors, Edwin Jager and Magnus Berggren, Nano-fiber scaffold electrodes based on PEDOT for cell stimulation, 2009, SENSORS AND ACTUATORS B-CHEMICAL, (142), 2, 451-456.http://dx.doi.org/10.1016/j.snb.2009.04.062Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/

We have developed a micromechanical stimulation chip that can apply physiologically relevant mechanical stimuli to single cells to study mechanosensitive cells in the urinary tract. The chips comprise arrays of microactuators based on the electroactive polymer polypyrrole (PPy). PPy offers unique possibilities and is a good candidate to provide such physiological mechanical stimulation, since it is driven at low voltages, is biocompatible, and can be microfabricated. The PPy microactuators can provide mechanical stimulation at different strains and/or strain rates to single cells or clusters of cells, including controls, all integrated on one single chip, without the need to pre-prepare the cells. The chips allow for in situ stimulation during live imaging studies. The use of these devices will increase experimental quality and reduce the number of biological samples. These unique tools fill an important gap in presently available tools, since the chips provide array-based stimulation patterns and are easily integrated in existing cell biology equipment. These chips will generate a leap forward in our understanding of the mechanisms involved in mechanotransduction in cells that may lead to breakthroughs, for instance in therapies for urinary incontinence.

Within the areas of cell biology, biomedicine and minimal invasive surgery, there is a need for soft, flexible and dextrous biocompatible manipulators for handling biological objects, such as single cells and tissues. Present day technologies are based on simple suction using micropipettes for grasping objects. The micropipettes lack the possibility of accurate force control, nor are they soft and compliant and may thus cause damage to the cells or tissue. Other micromanipulators use conventional electric motors however the further miniaturization of electrical motors and their associated gear boxes and/or push/pull wires has reached its limits. Therefore there is an urgent need for new technologies for micromanipulation of soft biological matter. We are developing soft, flexible micromanipulators such as micro- tweezers for the handling and manipulation of biological species including cells and surgical tools for minimal invasive surgery. Our aim is to produce tools with minimal dimensions of 100 μm to 1 mm in size, which is 1-2 orders of magnitude smaller than existing technology. We present newly developed patterning and microfabrication methods for polymer microactuators as well as the latest results to integrate these microactuators into easy to use manipulation tools. The outcomes of this study contribute to the realisation of low-foot print devices articulated with electroactive polymer actuators for which the physical interface with the power source has been a significant challenge limiting their application. Here, we present a new bottom-up microfabrication process. We show for the first time that such a bottom-up fabricated actuator performs a movement in air. This is a significant step towards widening the application areas of the soft microactuators.

By-pass surgery and heart transplantation are traditionally used to restore the heart’s functionality after a myocardial Infarction (MI or heart attack) that results in scar tissue formation and impaired cardiac function. However, both procedures are associated with serious post-surgical complications. Therefore, new strategies to help re-establish heart functionality are necessary. Tissue engineering and stem cell therapy are the promising approaches that are being explored for the treatment of MI. The stem cell niche is extremely important for the proliferation and differentiation of stem cells and tissue regeneration. For the introduction of stem cells into the host tissue an artificial carrier such as a scaffold is preferred as direct injection of stem cells has resulted in fast stem cell death. Such scaffold will provide the proper microenvironment that can be altered electronically to provide temporal stimulation to the cells. We have developed an electroactive polymer (EAP) scaffold for cardiac tissue engineering. The EAP scaffold mimics the extracellular matrix and provides a 3D microenvironment that can be easily tuned during fabrication, such as controllable fibre dimensions, alignment, and coating. In addition, the scaffold can provide electrical and electromechanical stimulation to the stem cells which are important external stimuli to stem cell differentiation. We tested the initial biocompatibility of these scaffolds using cardiac progenitor cells (CPCs), and continued onto more sensitive induced pluripotent stem cells (iPS). We present the fabrication and characterisation of these electroactive fibres as well as the response of increasingly sensitive cell types to the scaffolds.

There is a growing demand for human-friendly robots that can interact and work closely with humans. Such robots need to be compliant, lightweight and equipped with silent and soft actuators. Electroactive polymers such as conducting polymers (CPs) are “smart” materials that deform in response to electrical simulation and are often addressed as artificial muscles due to their functional similarity with natural muscles. They offer unique possibilities and are perfect candidates for such actuators since they are lightweight, silent, and driven at low voltages. Most CP actuators are fabricated using electrochemical oxidative synthesis. We have developed new CP based fibres employing both vapour phase and liquid phase electrochemical synthesis. We will present the fabrication and characterisation of these fibres as well as their performance as linear actuators.

Polypyrrole (PPy) is a conducting polymer that enables controlled drug release upon electrical stimulation. We characterized the biocompatibility of PPy with human primary osteoblasts, and the effect of dopants. We investigated the biocompatibility of PPy comprising various dopants, i.e. p-toluene sulfonate (PPy-pTS), chondroitin sulfate (PPy-CS), or dodecylbenzenesulfonate (PPy-DBS), with human primary osteoblasts. PPy-DBS showed the roughest appearance of all surfaces tested, and its wettability was similar to the gold-coated control. The average number of attached cells was 45% higher on PPy-DBS than on PPyCS or PPy-pTS, although gene expression of the proliferation marker Ki-67 was similar in osteoblasts on all surfaces tested. Osteoblasts seeded on PPy-DBS or gold showed similar vinculin attachment points, vinculin area per cell area, actin filament structure, and Ferets diameter, while cells seeded on PPY-CS or PPY-pTS showed disturbed focal adhesions and were enlarged with disorganized actin filaments. Osteoblasts grown on PPy-DBS or gold showed enhanced alkaline phosphatase activity and osteocalcin gene expression, but reduced osteopontin gene expression compared to cells grown on PPy-pTS and PPy-CS. In conclusion, PPy doped with DBS showed excellent biocompatibility, which resulted in maintaining focal adhesions, cell morphology, cell number, alkaline phosphatase activity, and osteocalcin gene expression. Taken together, conducting polymers doped with DBS are well tolerated by osteoblasts. Our results could provide a basis for the development of novel orthopedic or dental implants with controlled release of antibiotics and pharmaceutics that fight infections or focally enhance bone formation in a tightly controlled manner. Funding Agencies|VINNOVA [2012-04409]; Vetenskapradet [521-2013-2593]; Linkoping Initiative in Life Science Technologies (LIST)

Conducting polymers such as polypyrrole are biocompatible materials used in bioelectronic applications and microactuators for mechanobiology and soft microrobotics. The materials are commonly electrochemically synthesised from an electrolyte solution comprising pyrrole monomers and a salt, which is incorporated as the counter ion. This electrosynthesis results in polypyrrole forming a three-dimensional network with extensive cross-linking in both the alpha and beta positions, which impacts the electro-mechanical performance. In this study we adopt a blocking strategy to restrict and control cross-linking and chain branching through beta substitution of the monomer to investigate the effect of crosslinking on the electroactive properties. Methyl groups where used as blocking groups to minimise the impact on the pyrrole ring system. Pyrrole, 3- and 3,4-methyl substituted pyrrole monomers were electro-polymerised both as homo-polymers and as a series of co-polymer films. The electroactive performance of the films was characterised by measuring their electrochemical responses and their reversible and non-reversible film thickness changes. This showed that altering the degree of crosslinking through this blocking strategy had a large impact on the reversible and irreversible volume change. These results elaborate the importance of the polymer structure in the actuator performance, an aspect that has hitherto received little attention. Funding Agencies|EPSRC [EPP/504880/1]; EU-FP7-Erasmus; European Science Foundation COST Action [MP1003]; ESNAM (European Scientific Network for Artificial Muscles); Swedish Foundation for Strategic Research (SSF) [COST-STSM-MP1003-11581]; Linkoping University

The development of new conjugated-polymer tools for the study of the biological realm, and for use in a clinical setting, is reviewed in this article. Conjugated-polymer actuators, based on the changes of volume of the active conjugated polymer during redox transformation, can be used in electrolytes employed in cell-culture media and in biological fluids such as blood, plasma, and urine. Actuators ranging in size from 10 μm to 100 μm suitable for building structures to manipulate single cells are produced with photolithographic techniques. Larger actuators may be used for the manipulation of blood vessels and biological tissue. Original Publication:Charlotte Immerstrand, Kajsa Holmgren Peterson, Karl-Eric Magnusson, Edwin Jager, Magnus Krogh, Mia Skoglund, Anders Selbing and Olle Inganäs, Conjugated-Polymer Micro- and Milliactuators for Biological Applications, 2002, MRS bulletin, (27), 6, 461-464.http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=2959&DID=171856&action=detailCopyright: MRS Materials Research Societyhttp://www.mrs.org/

We present the development of a cell clinic. This is a micromachined cavity, or microvial, that can be closed with a lid. The lid is activated by two polypyrrole/Au microactuators. Inside the microvials two Au electrodes have been placed in order to perform impedance studies on single or a small number of cells. We report on impedance measurements on Xenopus leavis melanophores. We could measure a change in the impedance upon cell spreading and identify intracellular events such as the aggregation of pigment granules. The electrical data is correlated to optical microscopy.

Cardiac tissue engineering via the use of stem cells is the future for repairing impaired heart function that results from a myocardial infarction. Developing an optimised platform to support the stem cells is vital to realising this, and through utilising new 'smart' materials such as conductive polymers we can provide a multi-pronged approach to supporting and stimulating the stem cells via engineered surface properties, electrical, and electromechanical stimulation. Here we present a fundamental study on the viability of cardiac progenitor cells on conductive polymer surfaces, focusing on the impact of surface properties such as roughness, surface energy, and surface chemistry with variation of the polymer dopant molecules. The conductive polymer materials were shown to provide a viable support for both endothelial and cardiac progenitor cells, while the surface energy and roughness were observed to influence viability for both progenitor cell types. Characterising the interaction between the cardiac progenitor cells and the conductive polymer surface is a critical step towards optimising these materials for cardiac tissue regeneration, and this study will advance the limited knowledge on biomaterial surface interactions with cardiac cells.

Polypyrrole (PPy) hybrid films incorporated with porous carbide-derived carbon (CDC) particles are synthesized through a novel one-step electrochemical synthesis process that provides a simple and efficient alternative for current tape-casting and inkjet printing technologies to make conducting polymer-CDC-based electroactive composites. The resulting porous, robust and electrically conductive hybrid layer was used to fabricate electroactive polymer actuators both as perpendicularly expanding actuators and as bending trilayer actuators. Raman and FTIR spectroscopy confirm successful incorporation of CDC in the PPy matrix. Cyclic voltammograms confirm slightly higher charging/discharging currents of the PPyCDC hybrid. This indicates the successful coupling of CDC in order to increase electric double-layer capacitance in the hybrid films. The maximum steady state electromechanical diametrical strain is 13% for hybrid material which is in the same order of magnitude as for PPy and 10x more than previously reported CDC films made with non-conducting polymer binders. Furthermore, the expanding actuators made from hybrid material are more efficient than non-modified PPy actuators, having doubled the amount of swelling per injected charge. This improvement is very important since the low energy efficiency is a major shortcoming for ionic electroactive polymers. The high pseudocapacitance makes these new hybrid materials also interesting for energy storage applications. Funding Agencies|COST Action [MP1003]; Carl Trygger Foundation [CTS 12:206]; Linkoping University; [COST-STSM-MP1003-10794]; [-12937]

Actuator systems based on conducting polymers, such as polypyrole, with which three-dimensional movement can be controlled, are described. The Figure shows a combination of two such microactuators which are used to “kick” a glass bead across the surface of a silicon wafer. The microfabrication methods used to produce the systems are described and the potential uses, for example microrobotic arms, discussed. DOI enligt publikationen fungerar ej:10.1002/1521-4095(200101)13:13.0.CO;2-I