Dielectric Elastomer Cooperative Microactuator Systems : DECMAS

This paper presents results of the first phase of “Dielectric Elastomer Cooperative Microactuator Systems” (DECMAS), a project within the German Research Foundation Priority Program 2206, “Cooperative Multistable Multistage Microactuator Systems” (KOMMMA). The goal is the development of a soft cooperative microactuator system combining high flexibility with largestroke/high-frequency actuation and self-sensing capabilities. The softness is due to a completely polymer-based approach using dielectric elastomer membrane structures and a specific silicone bias system designed to achieve large strokes. The approach thus avoids fluidic or pneumatic components, enabling, e.g., future smart textile applications with cooperative sensing, haptics, and even acoustic features. The paper introduces design concepts and a first soft, single-actuator demonstrator along with experimental characterization, before expanding it to a 3 × 1 system. This system is used to experimentally study coupling effects, supported by finite element and lumped parameter simulations, which represent the basis for future cooperative control methods. Finally, the paper also introduces a new methodology to fabricate metal-based electrodes of sub-micrometer thickness with high membrane-straining capability and extremely low resistance. These electrodes will enable further miniaturization towards future microscale applications

Finite element modeling and validation of a soft array of spatially coupled dielectric elastomer transducers

Dielectric elastomer (DE) transducers are suitable candidates for the development of compliant mechatronic devices, such as wearable smart skins and soft robots. If many independently-controllable DEs are closely arranged in an array-like configuration, sharing a common elastomer membrane, novel types of cooperative and soft actuator/sensor systems can be obtained. The common elastic substrate, however, introduces strong electro-mechanical coupling effects among neighboring DEs, which highly influence the overall membrane system actuation and sensing characteristics. To effectively design soft cooperative systems based on DEs, these effects need to be systematically understood and modeled first. As a first step towards the development of soft cooperative DE systems, in this paper we present a finite element simulation approach for a 1-by-3 silicone array of DE units. After defining the system constitutive equations and the numerical assumptions, an extensive experimental campaign is conducted to calibrate and validate the model. The simulation results accurately predict the changes in force (actuation behavior) and capacitance (sensing behavior) of the different elements of the array, when their neighbors are subjected to different electro-mechanical loads. Quantitatively, the model reproduces the force and capacitance responses with an average fit higher than 93% and 92%, respectively. Finally, the validated model is used to perform parameter studies, aimed at highlighting how the array performance depends on a relevant set of design parameters, i.e. DE-DE spacing, DE-outer structure spacing, membrane pre-stretch, array scale, and electrode shape. The obtained results will provide important guidelines for the future design of cooperative actuator/sensor systems based on DE transducers

Fully Polymeric Domes as High-Stroke Biasing System for Soft Dielectric Elastomer Actuators

The availability of compliant actuators is essential for the development of soft robotic systems. Dielectric elastomers (DEs) represent a class of smart actuators which has gained a significant popularity in soft robotics, due to their unique mix of large deformation (>100%), lightweight, fast response, and low cost. A DE consists of a thin elastomer membrane coated with flexible electrodes on both sides. When a high voltage is applied to the electrodes, the membrane undergoes a controllable mechanical deformation. In order to produce a significant actuation stroke, a DE membrane must be coupled with a mechanical biasing system. Commonly used spring-like bias elements, however, are generally made of rigid materials such as steel, and thus they do not meet the compliance requirements of soft robotic applications. To overcome this issue, in this paper we propose a novel type of compliant mechanism as biasing elements for DE actuators, namely a threedimensional polymeric dome. When properly designed, such types of mechanisms exhibit a region of negative stiffness in their force-displacement behavior. This feature, in combination with the intrinsic softness of the polymeric material, ensures large actuation strokes as well as compliance compatibility with soft robots. After presenting the novel biasing concept, the overall soft actuator design, manufacturing, and assembly are discussed. Finally, experimental characterization is conducted, and the suitability for soft robotic applications is assessed

Model-Based Design Optimization of Soft Polymeric Domes Used as Nonlinear Biasing Systems for Dielectric Elastomer Actuators

Due to their unique combination of features such as large deformation, high compliance, lightweight, energy efficiency, and scalability, dielectric elastomer (DE) transducers appear as highly promising for many application fields, such as soft robotics, wearables, as well as micro electromechanical systems (MEMS). To generate a stroke, a membrane DE actuator (DEA) must be coupled with a mechanical biasing system. It is well known that nonlinear elements, such as negative-rate biasing springs (NBS), permit a remarkable increase in the DEA stroke in comparison to standard linear springs. Common types of NBS, however, are generally manufactured with rigid components (e.g., steel beams, permanent magnets), thus they appear as unsuitable for the development of compliant actuators for soft robots and wearables. At the same time, rigid NBSs are hard to miniaturize and integrate in DE-based MEMS devices. This work presents a novel type of soft DEA system, in which a large stroke is obtained by using a fully polymeric dome as the NBS element. More specifically, in this paper we propose a model-based design procedure for high-performance DEAs, in which the stroke is maximized by properly optimizing the geometry of the biasing dome. First, a finite element model of the biasing system is introduced, describing how the geometric parameters of the dome affect its mechanical response. After conducting experimental calibration and validation, the model is used to develop a numerical design algorithm which finds the optimal dome geometry for a given DE membrane characteristics. Based on the optimized dome design, a soft DEA prototype is finally assembled and experimentally tested

NAGEKEO WOMEN'S CULTURAL STRUGGLE AS A FLORES SUB-CULTURE AGAINST THE FLOW OF CIVILIZATION'S PROGRESS

ABSTRACT HobaPojo is a traditional cloth from the Nagekeo district that is commonly used by Nagekeo women. However, the development of fashion with other motive trends made hobapojo less prestige and began to be abandoned. This qualitative study uses case studies, in-depth interviews with triangulation methods to achieve research credibility. Data was found that the hobapojo cloth was traditionally intended for Nagekeo women. The meaning contained in the cloth covers the entire life cycle to the death of Nagekeo woman. Hobapojo must be used in a variety of traditional events, like clothing, blankets, dance costumes, surrender at the wedding, and cut teeth until the luggage when he died. Hobapojo is also a handicraft product for Nagekeo women to support their lives and to drive the family economy. There are rules in the use of fabrics, and each motif represents the characteristics and thinking skills of the weavers as a form of existence and effort to preserve culture. Keywords; Culture; HobaPojo; Cultural Communication. ABSTRAK HobaPojo adalah kain tradisional dari distrik Nagekeo yang biasa digunakan oleh wanita Nagekeo. Namun, perkembangan mode dengan tren motif lainnya membuat hobapojo kurang gengsi dan mulai ditinggalkan. Penelitian kualitatif ini menggunakan studi kasus, wawancara mendalam dengan metode triangulasi untuk mencapai kredibilitas penelitian. Data ditemukan bahwa kain hobapojo secara tradisional ditujukan untuk wanita Nagekeo. Makna yang terkandung dalam kain mencakup seluruh siklus hidup sampai kematian wanita Nagekeo. Hobapojo harus digunakan dalam berbagai acara tradisional, seperti pakaian, selimut, kostum tari, pasrah di pesta pernikahan, potong gigi sampai koper ketika ia meninggal. Hobapojo juga merupakan produk kerajinan tangan untuk wanita Nagekeo untuk mendukung kehidupan mereka dan untuk mendorong ekonomi keluarga. Ada aturan dalam penggunaan kain, dan masing-masing motif mewakili karakteristik dan keterampilan berpikir para penenun sebagai bentuk keberadaan dan upaya untuk melestarikan budaya. Kata kunci; Budaya; HobaPojo; Komunikasi Budaya

Fully Polymeric Domes as High-Stroke Biasing System for Soft Dielectric Elastomer Actuators

The availability of compliant actuators is essential for the development of soft robotic systems. Dielectric elastomers (DEs) represent a class of smart actuators which has gained a significant popularity in soft robotics, due to their unique mix of large deformation (>100%), lightweight, fast response, and low cost. A DE consists of a thin elastomer membrane coated with flexible electrodes on both sides. When a high voltage is applied to the electrodes, the membrane undergoes a controllable mechanical deformation. In order to produce a significant actuation stroke, a DE membrane must be coupled with a mechanical biasing system. Commonly used spring-like bias elements, however, are generally made of rigid materials such as steel, and thus they do not meet the compliance requirements of soft robotic applications. To overcome this issue, in this paper we propose a novel type of compliant mechanism as biasing elements for DE actuators, namely a three-dimensional polymeric dome. When properly designed, such types of mechanisms exhibit a region of negative stiffness in their force-displacement behavior. This feature, in combination with the intrinsic softness of the polymeric material, ensures large actuation strokes as well as compliance compatibility with soft robots. After presenting the novel biasing concept, the overall soft actuator design, manufacturing, and assembly are discussed. Finally, experimental characterization is conducted, and the suitability for soft robotic applications is assessed

Ultra-bright and efficient single photon generation based on N-V centres in nanodiamonds on a solid immersion lens

Single photons are fundamental elements for quantum information technologies such as quantum cryptography, quantum information storage and optical quantum computing. Colour centres in diamond have proven to be stable single photon sources and thus essential components for reliable and integrated quantum information technology. A key requirement for such applications is a large photon flux and a high efficiency. Paying tribute to various attempts to maximise the single photon flux we show that collection efficiencies of photons from colour centres can be increased with a rather simple experimental setup. To do so we spin-coated nanodiamonds containing single nitrogen-vacancy colour centres on the flat surface of a ZrO2 solid immersion lens. We found stable single photon count rates of up to 853 kcts/s at saturation under continuous wave excitation while having excess to more than 100 defect centres with count rates from 400 kcts/s to 500 kcts/s. For a blinking defect centre we found count rates up to 2.4 Mcts/s for time intervals of several ten seconds. It seems to be a general feature that very high rates are accompanied by a blinking behaviour. The overall collection efficiency of our setup of up to 4.2% is the highest yet reported for N-V defect centres in diamond. Under pulsed excitation of a stable emitter of 10 MHz, 2.2% of all pulses caused a click on the detector adding to 221 kcts/s thus opening the way towards diamond based on-demand single photon sources for quantum applications

NAGEKEO WOMEN'S CULTURAL STRUGGLE AS A FLORES SUB-CULTURE AGAINST THE FLOW OF CIVILIZATION'S PROGRESS

HobaPojo is a traditional cloth from the Nagekeo district that is commonly used by Nagekeo women. However, the development of fashion with other motive trends made hobapojo less prestige and began to be abandoned. This qualitative study uses case studies, in-depth interviews with triangulation methods to achieve research credibility. Data was found that the hobapojo cloth was traditionally intended for Nagekeo women. The meaning contained in the cloth covers the entire life cycle to the death of Nagekeo woman. Hobapojo must be used in a variety of traditional events, like clothing, blankets, dance costumes, surrender at the wedding, and cut teeth until the luggage when he died. Hobapojo is also a handicraft product for Nagekeo women to support their lives and to drive the family economy. There are rules in the use of fabrics, and each motif represents the characteristics and thinking skills of the weavers as a form of existence and effort to preserve culture. HobaPojo adalah kain tradisional dari distrik Nagekeo yang biasa digunakan oleh wanita Nagekeo. Namun, perkembangan mode dengan tren motif lainnya membuat hobapojo kurang gengsi dan mulai ditinggalkan. Penelitian kualitatif ini menggunakan studi kasus, wawancara mendalam dengan metode triangulasi untuk mencapai kredibilitas penelitian. Data ditemukan bahwa kain hobapojo secara tradisional ditujukan untuk wanita Nagekeo. Makna yang terkandung dalam kain mencakup seluruh siklus hidup sampai kematian wanita Nagekeo. Hobapojo harus digunakan dalam berbagai acara tradisional, seperti pakaian, selimut, kostum tari, pasrah di pesta pernikahan, potong gigi sampai koper ketika ia meninggal. Hobapojo juga merupakan produk kerajinan tangan untuk wanita Nagekeo untuk mendukung kehidupan mereka dan untuk mendorong ekonomi keluarga. Ada aturan dalam penggunaan kain, dan masing-masing motif mewakili karakteristik dan keterampilan berpikir para penenun sebagai bentuk keberadaan dan upaya untuk melestarikan budaya

In situ Biofilm Quantification in Bioelectrochemical Systems by using Optical Coherence Tomography

Detailed studies of microbial growth in bioelectrochemical systems (BESs) are required for their suitable design and operation. Here, we report the use of optical coherence tomography (OCT) as a tool for in situ and noninvasive quantification of biofilm growth on electrodes (bioanodes). An experimental platform is designed and described in which transparent electrodes are used to allow real‐time, 3D biofilm imaging. The accuracy and precision of the developed method is assessed by relating the OCT results to well‐established standards for biofilm quantification (chemical oxygen demand (COD) and total N content) and show high correspondence to these standards. Biofilm thickness observed by OCT ranged between 3 and 90 μm for experimental durations ranging from 1 to 24 days. This translated to growth yields between 38 and 42 mgurn:x-wiley:18645631:media:cssc201800589:cssc201800589-math-0001  gurn:x-wiley:18645631:media:cssc201800589:cssc201800589-math-0002 −1 at an anode potential of −0.35 V versus Ag/AgCl. Time‐lapse observations of an experimental run performed in duplicate show high reproducibility in obtained microbial growth yield by the developed method. As such, we identify OCT as a powerful tool for conducting in‐depth characterizations of microbial growth dynamics in BESs. Additionally, the presented platform allows concomitant application of this method with various optical and electrochemical techniques

Diversity of Bifidobacteria within the Infant Gut Microbiota

Background The human gastrointestinal tract (GIT) represents one of the most densely populated microbial ecosystems studied to date. Although this microbial consortium has been recognized to have a crucial impact on human health, its precise composition is still subject to intense investigation. Among the GIT microbiota, bifidobacteria represent an important commensal group, being among the first microbial colonizers of the gut. However, the prevalence and diversity of members of the genus Bifidobacterium in the infant intestinal microbiota has not yet been fully characterized, while some inconsistencies exist in literature regarding the abundance of this genus. Methods/Principal Findings In the current report, we assessed the complexity of the infant intestinal bifidobacterial population by analysis of pyrosequencing data of PCR amplicons derived from two hypervariable regions of the 16 S rRNA gene. Eleven faecal samples were collected from healthy infants of different geographical origins (Italy, Spain or Ireland), feeding type (breast milk or formula) and mode of delivery (vaginal or caesarean delivery), while in four cases, faecal samples of corresponding mothers were also analyzed. Conclusions In contrast to several previously published culture-independent studies, our analysis revealed a predominance of bifidobacteria in the infant gut as well as a profile of co-occurrence of bifidobacterial species in the infant’s intestine