Symposium FB
Flexible and Stretchable Electronics: Materials, Devices and Applications


FB-1:L05  Laser Enhancement of Pristine PEDOT:PSS Conductivity and Applications in Organic Electronics
J. TROUGHTON1, J. Rodriguez-Pereira2, N. Peillon1, J. Macak2, T. Djenizian1, 3, M. Ramuz1, 1Ecole des Mines de Sainte Etienne, Gardanne, France; 2Center of Materials and Nanotechnologies, University of Pardubice, Pardubice, Czechia, 3Center of Physical-Chemical Methods of Research and Analysis, Al-Farabi Kazakh National University, Almaty, Kazakhstan

PEDOT:PSS is a widely used material in organic electronics. In bioelectronics PEDOT:PSS is one of the most common materials in OECTs, favored for its mechanical properties, ease of fabrication, and ionic/electronic transducing abilities. The conductivity of PEDOT:PSS is crucial, and normally controlled with additives although these detrimentally affecting fabrication, particularly the wettability of the solution and subsequent film homogeneity. Here we demonstrate the use of a 1064nm laser to control the conductivity of PEDOT:PSS without additives, over 3 orders of magnitude, reaching conductivities over 300 S/cm, on par with the use of additives. We show that a minimum laser fluence is required to initiate conductivity enhancement, above which a maximum conductivity is quickly achieved followed by a gradual reduction as the laser power increases. This conductivity change is correlated with multiple materials parameters including changes in surface roughness, film thickness, work function, ionic conductivity, and local bonding environment. In this context, a discussion of likely mechanisms is presented. Finally, this conductivity control is coupled with laser ablation to masklessly fabricate planar OECTs with performance similar to equivalent devices using standard additives.

FB-1:IL07  Electrodes by Selective Laser Sintering
M. HAUKKA, University of Jyväskylä, Department of Chemistry, Jyväskylä, Finland

During the past decade, three-dimensional printing has been exploited in fabrication of vast number of different type of objects. However, in most cases the focus has been on producing objects with desired mechanical and physical properties. Only recently, the focus has been shifting towards objects that also possess other properties such as chemical activity or electrical conductivity. We have recently utilized Selective Laser Sintering (SLS) technique for preparation of highly porous flow-through electrodes that can be used in electrocatalysis or in battery technologies such as redox-flow batteries.1 In SLS technique the conductive carbon material such as graphite or carbon nanotubes, is mixed with powdery supporting polymer for example polypropylene, polyamide, or polyurethane. The choice of the or the supporting polymer determines the mechanical properties of the printed electrode. By using polyurethane as the supporting matrix it is possible to produce flexible electrodes in which the conductivity is sensitive to pressure and mechanical stress.
1. Lahtinen, E.; Kukkonen, E.; Jokivartio, J.; Parkkonen, J.; Virkajärvi, J.; Kivijärvi, L.; Ahlskog, M.; Haukka, M. ACS Appl. Energy Mater. 2019, 2, 1314−1318.

FB-1:L08  Benefits and Challenges Associated to Oxide Coating of Metallic Nanowire Networks
C. SANCHEZ1, 2, A. Sekkat1, M. Akbari1, C. Crivello1, D.T. Papanastsaiou1, L. Bardet1, C. Jiménez1, D. Bellet1, D. Muñoz-Rojas1, 1Univ. Grenoble Alpes, LMGP, CNRS, Grenoble INP, Grenoble, France; 2Univ. Grenoble Alpes, CNRS, Grenoble INP, CERAG, Grenoble, France

Silver nanowire (AgNW) networks have been widely used as transparent electrodes (TE) due to their remarkable electrical and optical properties. However, morphological instabilities, low adhesion, ageing issues are still the major bottlenecks limiting their broader use. Recent studies described that the use of a conformal protective oxide layer around the nanowires can increase drastically the network's stability. Zinc oxide, tin oxide and aluminium oxide deposited by Atmospheric Pressure Spatial Atomic Layer Deposition showed a significant enhancement of both thermal and electrical stability compared with bare AgNWs. These oxide coatings not only provide network stability but can also promote adhesion even in high humid environments. This contribution presents a brief overview of the main benefits and challenges of the different oxides used to coat metallic nanowire networks for a broad variety of applications.

FB-1:L09  3D Printed Soft Organic Thermoelectric Generators
H.E. BAYSAL, F. Molina-Lopez, KU Leuven, Leuven, Belgium

The massive development of wearable electronic devices come with a demand of lightweight, and flexible/streatchable energy sources. Thermoelectrics (TEs) is a promising solution because it meets these requirements and can convert waste body heat into electricity for powering devices. Although inorganic TE materials perform better than organic thermoelectric (OTE) materials, they are brittle, toxic, rare, expensive and hard to process, in sharp contrast with their organic counterparts. However, most OTEs involve thin films integrated on planar devices, which are applicable only to in-plane thermal gradients. This prevents the applicability of OTEs in most real-life scenarios. In this coference, I will present 3D direct ink writing (DIW) of TE conjugated polymer pastes on flexible/stretchable substrates such as plastic films or PDMS. DIW of OTE materials combine the thermoelectric function with processing advantages such as simplicity, capability of manufacturing 3D complex shapes, and low cost. The shape freedom of DIW will allows us to produce free-standing high aspect ratio pillars on a flexible/stretchable substrate, enabling the development of trully 3D OTEs and other soft electronic devices.

FB-1:L10  Efficient and Stable Transparent Electrodes based on Silver Nanowire Networks
L. BARDET1, 2, M. Akbari1, C. Crivello1, L. Rapenne1 , H. Roussel1, M. Weber1, C. Jiménez1, D. Muñoz-Rojas1, A. Denneulin2, D. Bellet1, 1Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France; 2Univ. Grenoble Alpes, CNRS, Grenoble INP, LGP2, Grenoble, France

Transparent electrodes (TE) are key components in many devices such as solar cells, light-emitting devices, touch screens or transparent heaters. Among them, the most used technology is indium tin oxide (ITO), due to its good optical and electrical properties but ITO-based TE are brittle and expensive. Due to the growing interest of flexible devices, emerging technologies such as silver nanowire (AgNW) networks appear as good alternatives to ITO thanks to their high optical transparency, high electrical conductivity and high flexibility. In this work the main challenges for improving performance of AgNW-based TE will be discussed. First, we investigate capillary force-induced cold-welding on AgNW networks. This post-deposition treatment enables not only to decrease the electrical resistance at low temperature with similar efficiency as a thermal treatment, but also decreases surface roughness of network, which is a clear asset for integration with thin active layers. Then, we investigate the coating of AgNW networks with a conformal SnO2 layer by Spatial Atomic Layer Deposition. We exhibit that even thin SnO2 coating drastically enhances thermal, electrical and ageing stability of AgNW networks. In this work we will present several in situ experiments and future challenges.

FB-1:IL11  Printed and Flexible Electronics and Photonics with Graphene and 2D Materials for Sensing, Wearable Electronics and Bioelectronics
F. TORRISI, Imperial College London, London, UK

Graphene and related 2D materials (GRMs) hold a great potential for flexible electronics and optoelectronics. The production and deposition of thin films of GRM from solutions or inks is extremely attractive for printed electronic devices, viable for flexible electronics. GRM-based inks enable a large range of printed device and integration options, such as digital, lithographic printing and roll-to-roll coating, which are ideal to deposit patterned thin films. The exfoliation in liquid of layered bulk materials (such as graphite, MoS2 crystals, etc.) is a scalable approach ideal to produce inks. However, currently the low yield of this process, results in a low concentration of dispersed GRMs. I will give an overview on the development of high-yield production GRM-based solutions and inks, suitable for several priting processes enabling GRM-based printable and flexible (opto)electronic devices. Then I will show how careful tuning of the surface interaction and GRM deposition process enables printed electronic and optoelectronic devices from 2D material inks, such as Thin Film Transistors achieving electron mobility > 150 cm2 V-1 s-1 Finally, I will demonstrate how the biocompatible properties of graphene are suitable as neuron-interfacing electronics.

FB-1:L13  Plasmonic ITO Nanoparticles’ Ink for IR Thermo-enabled Applications on Flexible Substrates
A. MAZZOTTA, M. Carlotti, A. Ottomaniello, V. Mattoli, Center for Materials Interfaces, Italian Institute of Technology, Pontedera, Italy; A. Gabbani, M. Ruggeri, E. Fantechi, F. Pineider, A. Pucci, Department of Chemistry, University of Pisa, Pisa, Italy

In this study, we developed a thermoplasmonic transparent ink based on a colloidal dispersion of indium-tin-oxide (ITO) nanoparticles which was transparent to visible light but able to generate heat by absorption of NIR radiation, for anti-counterfeiting applications. The functional ink can be inkjet printed on several substrates to prepare different motifs with high spatial resolution. By irradiating the devices with a NIR lamp, it was possible to perform a dynamic temperature mapping through a thermal camera. We built a demonstrator comprising a QR Code invisible to the naked eye which became visible in thermal images under NIR radiation. The high transparency of the printed ink (transmittance >99%) and the high speed of the thermal reading (figures appear/disappear in less than 1s) allow an effective fabrication and decryption of security labels against counterfeiting, offering a solution for low-cost, scalable production of photothermally active invisible labels. Due to the intrinsic thermo-modulable electrical condutivity, the ink can be used also in tailored sensing applications.

FB-1:L15  Solution-processed CuI for p-type Transparent Electronics
Kyunghan Ahn1, Ao Liu2, Yong-Young Noh2, Myung-Gil Kim1, 1School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon, South Korea; 2Dept. of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea

The transparent electronic materials are essential electronic components in large area electronics, such as display, thin-film solar cell, and wearable electronics. Although there have been great success on the n-type materials, such as ITO and a-IGZO, the p-type counterparts are still missing for industrial applications. To develop high performance p-type transparent electronic materials, we have investigated CuI, which has high intrinsic hole mobility (~40 cm2/Vs) and large optical band gap (3eV). In general, the facile Cu vacancy and I vacancy generation in CuI hinder the proper control of electrical properties of CuI. We have developed a mild processing of CuI with novel solution precursor, which enabled high performance thin-film transistor (mobility ~2 cm2/Vs) and high electrical conductivity electrode (conductivity > 200 S/cm). Transparent complementary inverters composed of p-type CuI and n-type indium gallium zinc oxide TFTs are demonstrated with clear inverting characteristics and voltage gain over 4. Our work suggests that CuI could be promising platform for complementary transparent electronic devices.

FB-1:L16  Easy Fabrication of Stretchable Waveguide for E-skin Applications
L. FLIEGANS, M. RAMUZ, S. BLAYAC, École des Mines de Saint-Étienne, Campus Georges Charpak Provence, Gardanne, France

For many years a strong research interest has been oriented towards soft electronics for artificial skin applications. However, one challenge with stretchable devices is the limited availability of high performance stretchable electrical conductors and semiconductors that could remained entirely stable while stretched. Moreover , examples of such electronic skin embed excess amount of wires for addressing each sensors (pressure or temperature) in the conventional matrix structure. Here, we present a new process for fabricating artificial skin consisting of an optical waveguide architecture allowing wide range of sensitivity to pressure [ 0 to 1KPa - 0.2 kPa ⁻¹ ], strain, shear and/or temperature variation [ 20 to 100°C - 0.01 °C ⁻¹], in multi-level ultra-stretchable network. The manufacturing process allows for a simple and low cost design of 100% low Young's modulus polymer [<1GPa]. This new type of stretchable optical sensor is highly robust, transparent and present a large sensing area [10 ✕ 10 cm²] with limited around of wires.Thus, this optical artificial skin presents far superior mechanical properties compare to current electronic skin.

FB-1:L17  Fabrication of Inkjet Printed Tunable BST/P(VDF-TrFE) Dielectrics for Flexible Varactors
T.P. MACH, J.R. Binder, Institute for Applied Materials (IAM-ESS), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany

Printed electronics are gaining more attention due to their ability to produce electrical components. For wireless communication, the high-frequency range plays an important role, which makes flexible components such as varactors interesting. Here, the ceramic or polymer dielectric is responsible for the dielectric properties. However, as both come with their own drawbacks, ceramic-polymer composites can be used to combine the excellent dielectric characteristics of ceramics and the easy processibility and flexibility of polymers. Furthermore, to obtain flexible varactors, inkjet printing offers a well-established method for the preparation in a fast and precise manner. In previous works, an inkjet printed capacitor system consisting of (Ba,Sr)TiO3)/PMMA has already been successfully implemented. However, for varactors, tunability can be achieved in a BST/P(VDF-TrFE) system with the introduction of ferroelectric PVDF based polymers. Herein, printable inks were developed with varying ratio between BST and P(VDF-TrFE) to achieve high tunability and low dielectric losses. Through rheological property and drying temperature adjustments, the so-called coffee stain effect can be prevented. Therefore, thin layers can be realized and characterized on their dielectric properties.

FB-2:L01  Study in Operando of Organic Semiconductor Stretchability
V. LAFARGE, C. Serbutoviez, M. Benwadih, A. Revaux, Univ. Grenoble Alpes, CEA, Liten, DTNM, Grenoble, France

Stretchability of organic semi-conductors (OSC) is investigated for few years for applications in wearable electronics or electronic skin thanks to their mechanical capacity compared to their inorganic equivalent. This study aims at understanding the link between OSC structural and morphological properties (crystallinity, alkyl chain length, Mw…) and their electrical and mechanical properties. Advanced mechanical, electrical and optical characterizations are carried out in operando on a specific homemade tensile bench to investigate OSC properties under traction. Mainly, a TLM (Transfer Length Measurement) structure with gold electrodes is used to follow contact and OSC resistivity during lengthening. The traction is realized with a micrometric plate, electrical measurements are made with a switching card and a multimeter, and a camera allows to measure at each moment the distance between the electrodes. We choose to study P3HT( poly(3- hexylthiophene)), which is a well documented material. The fact that it can be obtained in amorphous or semi-crystalline form (regiorandom or regioregular) and for various molecular weights makes the P3HT a good candidate for our study on the link between polymer structure and mechanical properties.

FB-2:IL02  Soft Electronic and Robotic Systems from Resilient yet Biocompatible and Degradable Materials
M. KALTENBRUNNER, Department of Soft Matter Physics, Johannes Kepler University Linz, Linz, Austria

Nature inspired a broad spectrum of bio-mimetic systems – from soft actuators to perceptive electronic skins – capable of sensing and adapting to their complex erratic environments. Yet, they are missing a feature of nature’s designs: biodegradability. Soft electronic and robotic devices that degrade at the end of their life cycle reduce electronic waste and are paramount for a sustainable future. At the same time, medical and bioelectronics technologies have to address hygiene requirements. We introduce materials and methods including tough yet biodegradable biogels for soft systems that facilitate a broad range of applications, from transient wearable electronics to metabolizable soft robots. These embodiments are reversibly stretchable, are able to heal and are resistant to dehydration. Our forms of soft electronics and robots – built from resilient biogels with tunable mechanical properties – are designed for prolonged operation in ambient conditions without fatigue, but fully degrade after use through biological triggers. Electronic skins merged with imperceptible foil technologies provide sensory feedback such as pressure, strain, temperature and humidity sensing in combination with untethered data processing and communication through a recyclable on-board computation unit.

FB-2:L03  Electro-mechanical Behaviour of Semiconducting Nanonets
S. SHARMA1, F. Morisot1, T. Arjmand1, M. Braccini1, F. Volpi2, C. Ternon1, 1Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France; 2Univ. Grenoble Alpes, CNRS, Grenoble INP, SIMaP, Grenoble, France

An innovative and promising alternative for future electronics is the integration in devices of semiconducting metal oxide nanonets, which are two dimensional network of interconnected nanowires randomly oriented in the plane. The merits are easy low cost integration process with high fault tolerance, good reproducibility and large surface area. Integration of these nanonets on flexible devices will thus help us in exploiting simultaneously the electrical and mechanical properties. Then, the aim of this work is to study the impact of electro-mechanical on device performance. With devices integrated on flexible kapton substrates, bending tests will be conducted to understand the current evolution in nanonet with changes in radius of curvature of flexible substrate. In parallel, a setup for conducting traction test in situ SEM along with electrical characterization will provide us current evolution characteristics on exposure to elongation and compression in the nanonet structure under traction. Finally, by combining SEM observations with electrical performance under bending and traction for various device geometries, we will gain a better understanding of nanonet behaviour.

FB-3:IL02  Soft Neuromorphic Computing
M.J. Mirshojaeian Hosseini1, Yi Yang1, E. Donati2, T. Yokota3, S. Lee3; G. Indiveri2, T. Someya3, R.A. Nawrocki1, 1School of Engineering Technology, Purdue University, West Lafayette, IN, USA; 2Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland; 3Department of Electrical and Electronics Engineering, The University of Tokyo, Tokyo, Japan

Spiking Neural Networks (SNN) provide distributed computation and emulate brain processing principles. With synapses and somas as their essential components, they function based on modulation of spike frequency and pulse width. Due to intrinsic compatibility with brain signaling, a target application of SNN hardware implementation, known as neuromorphic systems, are Brain-Computer Interfaces. They are typically implemented using hard, rigid, and non-biocompatible silicon technology, incompatible with brain's soft tissue. In organic electronics, we have fabricated physically flexible, spiking synaptic and somatic circuits. Complimentary p- and n-type organic transistors were fabricated on 50 μm thin Polyimide substrates, with DNTT and PDI8-CN2 (aka N1200) used as p- and n-type organic semiconductors, and Parylene diX-SR as the transistor and fabrication-integrated capacitor dielectric. Results show that organic spiking Integrate-and-Fire Axon-Hillock artificial soma integrates input currents and produces proportional output spikes. Also, Log-Domain Integrator and Differential-Pair Integrator synaptic circuits produce proportional output currents based on continuously tunable synaptic weights. Other critical circuit functions are also shown.

FB-3:L03  Silver Nanowire Networks for Stretchable Energy Harvesters: Properties and Challenges
D.T. Papanastasiou1, S.E. Haim2, A. Sylvestre2, S. Basrour3, D. Bellet1, 1Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France; 2Univ. Grenoble Alpes, CNRS, Grenoble INP, G2Elab, Grenoble, France; 3Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMA, Grenoble, France

Elastomer electrostatic generators and piezoelectrets are interesting components for devices widely used in the IoT, including smart clothes, biomechanical harvesters and sensors, haptic screens and soft robotics. In order to collect efficiently the electrical current generated by the mechanical deformation and integrate the harvesters into such emerging devices, there is a clear need for suitable electrical contacts. Thin gold films or conductive pastes traditionally used show poor stability under mechanical stress and insufficient optical transparency. Among the transparent conductive materials, silver nanowire (AgNW) networks are one of the most promising candidates to replace the traditional contacts. With 90% transmittance and 10 Ω/sq sheet resistance, superior mechanical properties and low cost fabrication, AgNW networks have attracted a huge interest the last years. Our approach is a three-layered structure, AgNW/PDMS/AgNW, to collect the charges from the PDMS biocompatible electroactive polymer. AgNW networks on PDMS exhibit highly stable electrical properties under elongation>30%. Besides, we focus on the investigation of AgNW stability issues and ways to enhance their performance, as well as the optimization of PDMS piezoelectret and the use of other elastomers too.

FB-3:IL04  Organic Neuromorphic Electronics and Biohybrid Systems
Y. VAN DE BURGT, Eindhoven University of Technology, Eindhoven, Netherlands

Neuromorphic computing could address the inherent limitations of conventional silicon technology in dedicated machine learning applications. However, delivering a compact and efficient parallel computing technology that is capable of embedding artificial neural networks in hardware remains a significant challenge. Organic electronic materials have shown potential to overcome some of these limitations. This talk describes state-of-the-art organic neuromorphic devices and provides an overview of the current challenges in the field and attempts to address them. I demonstrate a concept based on novel organic mixed-ionic electronic materials and show how we can use these devices in trainable biosensors and smart autonomous robotics. Next to that, organic electronic materials have the potential to operate at the interface with biology. This can pave the way for novel architectures with bio-inspired features, offering promising solutions for the manipulation and the processing of biological signals and potential applications ranging from brain-computer-interfaces and smart robotics to bioinformatics. I will highlight our recent efforts for such hybrid biological memory devices.

FB-3:IL09  Flexible and Printed Sensors and Biosensors: From Materials and Processes to Systems and Applications
L. PETTI, P. LUGLI, Free University of Bozen, Bolzano, Italy

Thanks to the extraordinary advances experienced by flexible electronics, it is now possible to realize electronic devices that ubiquitously conform to any complex surface and/or degrade in specific environments. To realize these devices, printing technologies play a key role, offering advantages such as cost-effectiveness, large-area scalability, as well as availability of a wide range of sustainable and biocompatible/biodegradable substrates and materials. Very recently, direct lasing of flexible or paper substrates to laser graphitize carbon-rich substrates has also gained increasingly attention. Here, our recent work in the field of cost-effective and high throughput processing of flexible electronic devices will be shown. Firstly, we will present a wide range of different sensors and biosensors realized using both printing and laser induced graphitization (LIG) on different types of substrates (e.g., polyimide, paper) will be presented. Next, characterization of mechanical (bending, stretching) and chemical (dissolubility) characteristics will be displayed. Finally, we will discuss applications of these innovative components in both wearable sports and healthcare applications, as well as in the field of precision agriculture and food quality and control monitoring.

FB-3:IL10  Biomaterial Lasers for Sensing and Imaging
M. Humar, J. Stefan Institute, Ljubljana, Slovenia; Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; CENN Nanocenter, Ljubljana, Slovenia

Photonic components made from biological materials and integrated into live biological organisms have the potential to enable novel applications including ultrasensitive sensing and new imaging modalities. This perspective has motivated recent efforts in developing lasers and other optical devices that are made, in part or entirety, of biological or biocompatible materials. I will present our recent research on the development of these biological optical components and their applications in the study of biophysical and biochemical processes. Notably, we have for the first time demonstrated a laser completely embedded inside a live human cell. The intracellular lasers can act as very sensitive sensors, enabling us to better understand cellular processes. Each laser within a cell emits light with a slightly different fingerprint which can be used as a barcode to tag millions of cells, providing the ability the study cell migration. Further, by using a deformable droplet laser, we can measure very precisely the forces acting within a single cell. Finally, lasers embedded into tissues may enable new diagnostic, treatment and imaging tools in medicine and biology.

FB-3:IL11  Flexible and Reliable Organic Solar Cell
Kenjiro Fukuda1, T. Someya1, 2, 1RIKEN, Saitama, Japan; 2The University of Tokyo, Japan

The development of lightweight and flexible energy harvesting system is an important challenge toward wearable electronics such as on-skin sensors and smart textiles. Organic solar cells using polymers as the active layer is one of the most promising energy harvesting system due to their high-power output per unit area, flexibility, and conformability. Recently we have achieved ultra-thin organic solar cells having more than 12% of power conversion efficiency and good mechanical robustness. In this talk I will introduce our recent progress of ultra-flexible organic solar cells and potential applications of such ultra-flexible solar cells for wearable electronics.

FB-3:IL12  Computational and Physical Optical Models of the Eye for Medical Applications
M. RAMUZ, S. regal, Flexible Electronics Department, Mines St Etienne, Gardanne, France

The eye is a sophisticated system of optical elements for the preeminent sense of vision. In recent years, the number of laser surgeries allowing the correction of different optical aberrations has significantly increased. Consequently, improve the knowledge related to the interactions of light with the eye is crucial in order to enhance the efficiency and safety of the surgery. We present here the development of physical and computational models of the eye in order to reproduce its optical properties. We have developed a phantom eye in order to mimic the different parts/tissues like for e.g. the sclera or the ciliary body as finely as possible regarding the optical properties. For the development of these models, we used the optical parameters (absorption and scattering coefficients and refractive index) extracted from an experimental study carried out on porcine eyes – which are close to human one. All the different parts are put together to obtain a device mimicking exactly the optical properties of an eye with the integration of opto-electronic devices in order to evaluate light propagation into this organ. These models would be helpful to develop new procedures for laser surgery as well as the development of new equipment for ophthalmology or medical applications.

FB-3:IL13  Wireless Epidermal Electronic System to Simultaneously Measure Electrocardiograms and Seismocardiograms from Human Body
M.E. Hesar, N. Seyedsadrkhani, D. Khan, S. Ingebrandt, Institute of Materials in Electrical Engineering 1, RWTH Aachen University, Aachen, Germany

Electrocardiography (ECG) can be measured by integrated epidermal electronic systems and is a widespread technique in the healthcare system. Seismocardiography (SCG), which measures the vibration of the chest due to the mechanical activity of the heart, is used to a much lesser extent. In our study, we developed a combined system as a smart skin patch based on a thin film of piezoelectric Polyvinylidene difluoride (PVDF) on Polyimide (PI). A multi-level system-in-a-foil was fabricated including amplifier circuit, contact lines; coil for telemetry and through contacts from layer-to-layer, which offers simultaneous ECG and SCG recordings. Using an onboard amplifier circuit, the signals can be measured by a near field communication (NFC) reader, which is also used to power the whole circuit. Measurements showed a good signal-to-noise ratio of both readout signals. The microcontroller in our system-in-a-foil offers more input channels, which we intent to use for future sensor-fusion applications towards modern healthcare.

FB-3:IL14  Thermoelectric-based Adjustable Wearable Camouflage Devices
SUNMI SHIN, Department of Mechanical Engineering, National University of Singapore, Singapore

Thermal cloaking and camouflage have attracted increasing attention with the progress of infrared surveillance technologies. Previous studies have been mainly focused on emissivity manipulation or using sophisticated thermal metamaterials. However, emissivity control is only applicable for objects that are warmer than the environment and lower emissivity is usually accompanies with high reflectance of the surrounding thermal signals if they have nonuniform temperature. Metamaterial-based thermal camouflage holds great promise but their applications on human subjects are yet to be realized. Direct temperature control represents a more desirable strategy to realize dynamically adjustable camouflage within a wide ambient temperature range, but a wearable, portable, and adjustable thermo-regulation system that is suitable for human subjects have been developed. I will present a wearable and adaptive infrared camouflage device responding to the background temperature change based on the thermoelectric cooling and heating effect. The flexible thermoelectric device can realize the infrared camouflage effect to effectively shield the metabolic heat from skin within a wide range of background temperature, showing promise for a broad range of potential applications.


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