The authors would like to acknowledge the BPI PIAVE AUTONOTEX grant for the financial support.

1. Patterning Conducting Polymers on Textile
<ol>
	<li>Fix a 10 cm x 10 cm textile sheet on a planar surface for easy handling during the process. For the textile, use a 100% interlock knit polyester fabric with a thickness of 300 &#181;m and a knit direction stretch capability up to 50%.</li>
	<li>To make a mask containing the patterning design, use a 125 &#181;m-thick polyimide film; an example of the pattern is illustrated in Figure 1.
	<ol>
		<li>Use a laser cutter (e.g., Protolaser S, LPKF) to pattern the polyimide mask10; the pattern design of an electrode is illustrated in Figure 1.</li>
		<li>Coat the PDMS formulation (10:1 base to curing agent ratio) on top of the mask (polyimide film) using an automatic tape casting tool (K control print-coater, doctor blade) with a wet film thickness of 200 &#181;m and at a 6 m/min coating speed. Use about 0.5 mL for a mask of 3 cm x 5 cm. Perform this process under the fume hood.</li>
	</ol>
	</li>
	<li>Gently transfer the fabric to the PDMS-coated mask. Leave for 10 min, after which the PDMS should be fully absorbed in the textile structure.</li>
	<li>Cure the sample in an air-oven at 100 &#176;C for 10 min.</li>
	<li>Prepare the conducting polymer:PEDOT:PSS dispersion (80 mL), ethylene glycol (20 mL), 4-dodecylbenzenesulfonic acid (40 &#181;L), and 3-methacryloxypropyltrimethoxysilane (1 mL) in the fume hood.</li>
	<li>Brush-coat the PEDOT:PSS solution on the PDMS-free area of the textile until a homogenous penetration of the solution is obtained. Repeat this step to achieve a uniform pattern color. Apply about 1 mL/cm2.</li>
	<li>Cure the fabric at 110 &#176;C for 1 h to dry the PEDOT:PSS solution. Reduce the temperature to 60 &#176;C for textiles that are sensitive to high-temperature treatment, like nylon.</li>
</ol>
2. Organic Device Fabrication
NOTE: The protocol in Section 1 describes the selective deposition of conducting materials on textiles. The following sections will describe the additional steps needed to fabricate organic devices, like stretch sensors, OECT transistors, cutaneous electrodes, and capacitive sensors.
<ol>
	<li>To fabricate stretch sensors, shown in Figure 3a, pattern the electrode lines on the textile, as described in Section 1, steps 1.1-1.5. 
	NOTE: An example of the pattern design is shown in Figure 3a. The fabrication of such sensors does not require any additional steps.</li>
	<li>To fabricate the transistor design shown in Figure 3b, pattern the transistor arrays on a nylon woven ribbon following the steps described in Section 1. Slightly modify the PDMS annealing and PEDOT:PSS curing steps to avoid the thermal degradation of nylon by curing at 60 &#176;C for a longer time.</li>
	<li>For the fabrication of cutaneous electrodes, shown in Figure 3c, deposit an ionic gel on the patterned PEDOT:PSS textiles.
	<ol>
		<li>Prepare an ionic liquid gel mixture containing the ionic liquid, 1-ethyl-3-methylimidazolium-ethyl sulfate; the cross-linking agent, poly(ethylene glycol)diacrylate; and the photoinitiator, 2-hydroxy-2-methylpropiophenone at a (v/v) ratio of 0.6/0.35/0.05, respectively.</li>
		<li>Coat the PEDOT:PSS electrode with ionic liquid (20 &#181;L/cm2) and add the ionic liquid gel mixture from step 2.3.1 (25 &#181;L/cm2) by drop casting.</li>
		<li>Expose to UV light (365 nm) to initiate a crosslinking reaction for 10-15 min, until the gel solidifies. Perform this step in the fume hood. Use a UV-protective cage during UV exposure.</li>
	</ol>
	</li>
	<li>For capacitive sensor fabrication, use PEDOT:PSS textile electrodes insulated with an insulating material (Figure 3d).
	<ol>
		<li>Insulate the keyboard-like PEDOT:PSS electrodes using the PDMS; the keyboard design can be seen in Figure 2b. Dispense the PDMS formulation on top of the fabric and remove the excess with a squeegee.</li>
		<li>Place the fabric in an oven at 100 &#176;C for 10 min. Perform this step in the fume hood.</li>
	</ol>
	</li>
</ol>

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Microeng. 20, 075017 (2010).</li><li>Patel, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+wearable+sensors+and+systems+with+application+in+rehabilitation.">A review of wearable sensors and systems with application in rehabilitation.</a> J. Neuroeng. Rehabil. 9, 21 (2012).</li><li>Bandodkar, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidermal+tattoo+potentiometric+sodium+sensors+with+wireless+signal+transduction+for+continuous+non-invasive+sweat+monitoring.">Epidermal tattoo potentiometric sodium sensors with wireless signal transduction for continuous non-invasive sweat monitoring.</a> Biosens. Bioelectron. 54, 603-609 (2014).</li><li>Owens, R. M., Malliaras, G. 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The authors have nothing to disclose.

The patterning of conducting materials is one of the first steps in the fabrication of functional electronic devices. This can become challenging, as the fabrication process needs to take into account the chemical and physical properties of such materials, and the process flow needs to consider the material cross-compatibility between the fabrication steps. In the microfabrication of organic electronic devices, these two aspects are even more significant due to the highly reactive nature of organics. Today, however, orga...

The field of wearable electronics is a fast-growing market expected to be worth 50 billion euros in 2025, over three times the current market. The main challenge facing current wearable devices is that intrusive solid electronic attachments limit the usage of established devices in wearable systems. Using textiles that are already present in everyday life is a very attractive and straightforward approach to avoid this limitation. Due to its elastic capability, some parts of the clothing that we wear are naturally in tight contact with the skin. Many examples of smart clothes available on the market today are based on thin, plastic displays, keyboards, and light source devices embedded in textiles, linking electronics with humans in a fashionable way1. In sport practice, health monitoring relies on textile electrodes, which offer comfortable alternatives to commonly used adhesive electrodes and metal wristbands. Here, conductive fibers are directly integrated with stretchy fabrics to prevent skin irritation and other discomforts during extended wear. Additionally, textiles offer a number of opportunities to integrate curvature sensors to capture motion2, to integrate shear sensors for the development of functional robotic actuators3, and certainly to integrate biosensors through the detection of an analyte in sweat4.
Modern wearable technology relies on carbon-based semiconductor materials that deliver electronic devices with unique properties. The &#34;soft&#34; nature of organics offers better mechanical properties for interfacing with the human body compared to traditional solid-state electronics. This mechanical compatibility, paired with mechanically flexible substrates, enables the use of non-planar form factors in devices such as textiles. The use of organics is also relevant in life sciences due to their mixed electronic and ionic conductivity5. Besides, organic semiconducting and optoelectronic materials empower a large variety of functional devices with display, transistor, logic, and power capabilities6,7,8,9. The main difficulty in the fabrication of such organic devices is the controlled deposition of functional materials on the non-planar surfaces of textiles. Conventional microfabrication techniques are primarily limited by the incompatibility of the deposition process with the structural dimensionality of textile substrates.
Here, we describe a simple and scalable fabrication protocol that allows for the selective deposition of conducting polymers on structured textiles. The presented process enables the fabrication of wearable and conformal electronic devices. The approach is based on the patterning of the commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and an elastomeric stencil material polydimethylsiloxane (PDMS) on textile. This combination allows for the efficient confinement of the aqueous PEDOT:PSS solution, as well as for the retention of the soft and stretchable properties of textiles. This simple and reliable fabrication method paves the way for the fabrication of a variety of electronic devices directly on textiles in a cost-efficient and industrially scalable manner.

<table><tbody><tr><td>SYLGARD 184, Silicone elastomer kit (Base and Curing agent)</td><td>Dow Corning</td><td></td><td>PDMS elastomer</td></tr><tr><td colspan="4">&lt;strong&gt;The conducting polymer formulation&lt;/strong&gt;</td></tr><tr><td>CleviosTM PH 1000 PEDOT:PSS</td><td>Heraeus</td><td></td><td>Conductive polymer</td></tr><tr><td>Ethylene glycol</td><td>Sigma-Aldrich</td><td>03750-250ML</td><td>Solvent (EG), CAS: 107-21-1</td></tr><tr><td>3-methacryloxypropyltrimethoxysilane</td><td>Sigma-Aldrich</td><td>M6514</td><td>Cros linker (GOPs), CAS: 2530-85-0</td></tr><tr><td>4-dodecylbenzenesulfonic acid</td><td>Sigma-Aldrich</td><td>44198</td><td>DBSA; CAS: 121-65-3</td></tr><tr><td colspan="4">&lt;strong&gt;The ionic liquid gel&lt;/strong&gt;</td></tr><tr><td>UV lamp DFE 2340</td><td>C.I.F/ ATHELEC</td><td>DP134</td><td>UV-365 nm</td></tr><tr><td>1-Ethyl-3-methylimidazolium ethyl sulfate</td><td>Sigma-Aldrich</td><td>51682-100G-F</td><td>Ionic Liquid (IL), CAS: 342573-75-5</td></tr><tr><td>Poly(ethylene glycol) diacrylate</td><td>Sigma-Aldrich</td><td>455008-100ML</td><td>Mn 700, CAS: 26570-48-9</td></tr><tr><td>2-Hydroxy-2-methylpropiophenon</td><td>Sigma-Aldrich</td><td>405655-50ML</td><td>Phot Initiator (PI), CAS: 7473-98-5</td></tr><tr><td>The textile fabric</td><td>VWR</td><td>Spec-Wipe 7 Wipers</td><td>100% interlock knit polyester fabric</td></tr><tr><td>The polyimide film</td><td>DuPont</td><td>HN100</td><td>Polyimide film with 125 &amp;micro;m thickness</td></tr></tbody></table>

a simple and scalable fabrication method for organic electronic devices on textiles

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

Traditional methods for applying colors or patterns to textiles rely on removable masking layers to allow the selective deposition of dyes. In Figure 1, we show the adaptation of such an approach to the patterning of PEDOT:PSS electrodes on textiles. As a masking layer, we used hydrophobic polydimethylsiloxane, which can restrain the non-controllable diffusion of the aqueous PEDOT:PSS solution. Moreover, the softness and stretchability of knitted and woven textiles can be...

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

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

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

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Research

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Bioengineering

10.4K Views.  Ecole Nationale Supérieure des Mines de Saint-Étienne, CMP-EMSE, MOC. In this paper, we present a protocol to selectively deposit organic materials on textiles, which allows for the direct integration of organic electronic devices with wearables. The fabricated devices can be fully integrated in textiles, respecting their mechanical appearance and enabling sensing capabilities.

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

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult. Using a mini-slot die coater, this mismatch can be resolved by translating the commercial process to the laboratory and characterizing the structure formation in the active layer of the device in real time and in situ as films are coated onto a substrate. The evolution of the morphology was characterized under different conditions, allowing us to propose a mechanism by which the structures form and grow. This mini-slot die coater offers a simple, convenient, material efficient route by which the morphology in the active layer can be optimized under industrially relevant conditions. The goal of this protocol is to show experimental details of how a solar cell device is fabricated using a mini-slot die coater and technical details of running in situ structure characterization using the mini-slot die coater.

Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization

Here, we present a protocol to fabricate organic thin film solar cells using a mini-slot die coater and related in-line structure characterizations using synchrotron scattering techniques.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices ...

Engineering

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Sensing of Barrier Tissue Disruption with an Organic Electrochemical Transistor

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the passage of necessary ions and molecules. A breach in this barrier can be caused by a reduction in the extracellular calcium concentration. This reduction in calcium concentration causes a conformational change in proteins involved in the sealing of the barrier, leading to an increase of the paracellular flux. To mimic this effect the calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N&#39;,N&#39;-tetra acetic acid (EGTA) was used on a monolayer of cells known to be representative of the gastrointestinal tract. Different methods to detect the disruption of the barrier tissue already exist, such as immunofluorescence and&#160;permeability assays. However, these methods are time-consuming and costly and not suited to dynamic or high-throughput measurements. Electronic methods for measuring barrier tissue integrity also exist for measurement of the transepithelial resistance (TER), however these are often costly and complex. The development of rapid, cheap, and sensitive methods is urgently needed as the integrity of barrier tissue is a key parameter in drug discovery and pathogen/toxin diagnostics. The organic electrochemical transistor (OECT) integrated with barrier tissue forming cells has been shown as a new device capable of dynamically monitoring barrier tissue integrity. The device is able to measure minute variations in ionic flux with unprecedented temporal resolution and sensitivity, in real time, as an indicator of barrier tissue integrity. This new method is based on a simple device that can be compatible with high throughput screening applications and fabricated at low cost.

The Organic Electrochemical Transistor is integrated with live cells and used to monitor ion flux across the gastrointestinal epithelial barrier. In this study, an increase in ion flux, related to disruption of tight junctions, induced by the presence of the calcium chelator EGTA (ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetra acetic acid), is measured.

The gastrointestinal tract is an example of barrier tissue that provides a physical barrier against entry of pathogens and toxins, while allowing the ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Chemistry

Fabrication of Flexible Image Sensor Based on Lateral NIPIN Phototransistors

Flexible photodetectors have been intensely studied for the use of curved image sensors, which are a crucial component in bio-inspired imaging systems, but several challenging points remain, such as a low absorption efficiency due to a thin active layer and low flexibility. We present an advanced method to fabricate a flexible phototransistor array with an improved electrical performance. The outstanding electrical performance is driven by a low dark current owing to deep impurity doping. Stretchable and flexible metal interconnectors simultaneously offer electrical and mechanical stabilities in a highly deformed state. The protocol explicitly describes the fabrication process of the phototransistor using a thin silicon membrane. By measuring I-V characteristics of the completed device in deformed states, we demonstrate that this approach improves the mechanical and electrical stabilities of the phototransistor array. We expect that this approach to a flexible phototransistor can be widely used for the applications of not only next-generation imaging systems/optoelectronics but also wearable devices such as tactile/pressure/temperature sensors and health monitors.

We present a detailed method to fabricate a deformable lateral NIPIN phototransistor array for curved image sensors. The phototransistor array with an open mesh form, which is composed of thin silicon islands and stretchable metal interconnectors, provides flexibility and stretchability. The parameter analyzer characterizes the electrical property of the fabricated phototransistor.

Flexible photodetectors have been intensely studied for the use of curved image sensors, which are a crucial component in bio-inspired imaging systems, ...

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

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

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

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

Hybrid Printing for the Fabrication of Smart Sensors

A method to combine additively manufactured substrates or foils and multilayer inkjet printing for the fabrication of sensor devices is presented. First, three substrates (acrylate, ceramics, and copper) are prepared. To determine the resulting material properties of these substrates, profilometer, contact angle, scanning electron microscope (SEM), and focused ion beam (FIB) measurements are done. The achievable printing resolution and suitable drop volume for each substrate are, then, found through the drop size tests. Then, layers of insulating and conductive ink are inkjet printed alternately to fabricate the target sensor structures. After each printing step, the respective layers are individually treated by photonic curing. The parameters used for the curing of each layer are adapted depending on the printed ink, as well as on the surface properties of the respective substrate. To confirm the resulting conductivity and to determine the quality of the printed surface, four-point probe and profilometer measurements are done. Finally, a measurement set-up and results achieved by such an all-printed sensor system are shown to demonstrate the achievable quality.

Here we present a protocol for the fabrication of inkjet-printed multilayer sensor structures on additively manufactured substrates and foil.

A method to combine additively manufactured substrates or foils and multilayer inkjet printing for the fabrication of sensor devices is presented. First, ...

Development of Efficient OLEDs from Solution Deposition

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% internal quantum efficiency. Presented here is a solution deposition method for the fabrication of efficient organic light-emitting diodes (OLEDs) based on a TADF emitter in a simple device structure. This fast, low-cost, and efficient process can be used for all OLED emissive layers that follow the host-guest concept. The fundamental steps are described along with necessary information for further reproduction. The goal to establish a general protocol that can be easily adapted for principal organic emitters currently under study and development.

Presented here is a protocol for the fabrication of efficient, simple, solution-deposited organic light-emitting diodes with low roll-off.

The use of highly efficient organic emitters based on the thermally activated delayed fluorescence (TADF) concept is interesting due to their 100% ...

Fabrication of Fine Electrodes on the Tip of Hypodermic Needle Using Photoresist Spray Coating and Flexible Photomask for Biomedical Applications

We have introduced a fabrication method for electrical impedance spectroscopy (EIS)-on-a-needle (EoN: EIS-on-a-needle) to locate target tissues in the body by measuring and analyzing differences in the electrical impedance between dissimilar biotissues. This paper describes the fabrication method of fine interdigitated electrodes (IDEs) at the tip of a hypodermic needle using a photoresist spray coating and flexible film photomask in the photolithography process. A polyethylene terephthalate (PET) heat shrink tube (HST) with a wall thickness of 25 &#181;m is employed as the insulation and passivation layer. The PET HST shows a higher mechanical durability compared with poly(p-xylylene) polymers, which have been widely used as a dielectric coating material. Furthermore, the HST shows good chemical resistance to most acids and bases, which is advantageous for limiting chemical damage to the EoN. The use of the EoN is especially preferred for the characterization of chemicals/biomaterials or fabrication using acidic/basic chemicals. The fabricated gap and width of the IDEs are as small as 20 &#181;m, and the overall width and length of the IDEs are 400 &#181;m and 860 &#181;m, respectively. The fabrication margin from the tip (distance between the tip of hypodermic needle and starting point of the IDEs) of the hypodermic needle is as small as 680 &#181;m, which indicates that unnecessarily excessive invasion into biotissues can be avoided during the electrical impedance measurement. The EoN has a high potential for clinical use, such as for thyroid biopsies and anesthesia drug delivery in a spinal space. Further, even in surgery that involves the partial resection of tumors, the EoN can be employed to preserve as much normal tissue as possible by detecting the surgical margin (normal tissue that is removed with the surgical excision of a tumor) between the normal and lesion tissues.

The fabrication method for fine interdigitated electrodes (gap and width: 20 &#181;m) at the tip of a hypodermic needle (diameter: 720 &#181;m) is demonstrated using a spray coating and flexible film photomask in the photolithography process.

We have introduced a fabrication method for electrical impedance spectroscopy (EIS)-on-a-needle (EoN: EIS-on-a-needle) to locate target tissues in the ...

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

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