Name: fabrication of flexible image sensor based on lateral nipin phototransistors
Uploaded: 2018-06-23T14:00:00
Description: Watch this Scientific Journal Video about Fabrication of Flexible Image Sensor Based on Lateral NIPIN Phototransistors at JoVE.com

This research was supported by the Creative Materials Discovery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2017M3D1A1039288). Also, this research was supported by the Institute for Information and Communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (No.2017000709, Integrated approaches of physically unclonable cryptographic primitives using random lasers and optoelectronics).

CAUTION: Some chemicals (i.e., hydrofluoric acid, buffered oxide etchant, isopropyl alcohol, etc.) used in this protocol can be hazardous to health. Please consult all relevant material safety data sheets before any sample preparation takes place. Utilize appropriate personal protective equipment (e.g., lab coats, safety glasses, gloves) and engineering controls (e.g., wet station, fume hood) when handling etchants and solvents.
1. Si Doping and Isolation
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The fabrication technology described here contributes significantly to the progress of advanced electronics and wearable devices. The fundamental concepts of this approach use a thin Si membrane and metal interconnectors capable of stretching. Although Si is a brittle and hard material that can easily be fractured, a very thin Si layer can obtain a flexibility26,27. In the case of the metal interconnector, the wavy shape offers stretchability and flexibility<sup ...

Bio-inspired imaging systems can provide many advantages compared to the conventional imaging systems1,2,3,4,5. Retina or hemispherical ommatidia is a substantial component of biological visual system1,2,6. A curved image sensor, which mimics the critical element of animal eyes, can provide a compact and simple configuration of optical systems with low aberrations7. Diverse advancements of fabrication techniques and materials, for example, the use of intrinsically soft materials such as organic/nanomaterials8,9,10,11,12 and the introduction of deformable structures to semiconductors including silicon (Si) and germanium (Ge)1,2,3,13,14,15,16,17, realize the curved image sensors. Among them, Si-based approaches provide inherent advantages such as an abundance of material, mature technology, stability, and optical/electrical superiority. For this reason, although Si has intrinsic rigidity and brittleness, Si-based flexible electronics have been widely studied for various applications, such as flexible optoelectronics18,19,20 including curved image sensors1,2,3, and even wearable healthcare devices21,22.
In a recent study, we analyzed and improved the electrical performance of a thin Si photodetector array23. In that study, the optimum single unit cell of the curved photodetector array is a phototransistor (PTR) type that consists of a photodiode and blocking diode. The base junction gain amplifies a generated photocurrent, and hence it exhibits a route to improve an electrical performance with a thin film structure. In addition to the single cell, the thin film structure is suitable to suppress a dark current, which is considered as noise in the photodetector. Regarding doping concentration, a concentration larger than 1015 cm-3 is sufficient to achieve an exceptional performance in which the diode characteristics can be maintained with a light intensity over 10-3 W/cm2 23. Moreover, the PTR single cell has a low column noise and optically/electrically stable properties compared to that of the photodiode. Based on these design rules, we fabricated a flexible photodetector array that consists of thin Si PTRs using a silicon-on-insulator (SOI) wafer. In general, an important design rule of flexible image sensors is the neutral mechanical plane concept which defines the position through the thickness of the structure where strains are zero for an arbitrarily small r24. Another crucial point is a serpentine geometry of the electrode because a wavy shape provides fully reversible stretchability to the electrode. Due to these two important design concepts, the photodetector array can be flexible and stretchable. It facilitates the 3D deformation of the photodetector array into a hemispherical shape or a curved shape like the retina of animal eyes2.
In this work, we detail the processes for the fabrication of the curved PTR array using semiconductor fabrication processes (e.g., doping, etching, and deposition) and transfer printing. Also, we characterize a single PTR in terms of an I-V curve. In addition to the fabrication method and individual cell analysis, the electrical feature of the PTR array is analyzed in deformed states.

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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.

Figure 3a and 3b show the designed and fabricated structure of NIPIN PTR considering previous studies2,23. The inset in Figure 3a exhibits a basic I-V characteristic of PTR. The detailed structural parameters of PTR are shown in Figure 3b. The doping process for a Si layer on an SOI wafer was conducted using the ion implantat...

Watch this Scientific Journal Video about Fabrication of Flexible Image Sensor Based on Lateral NIPIN Phototransistors at JoVE.com

Fabrication of Flexible Image Sensor Based on Lateral NIPIN Phototransistors

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, ...

Our approach can help advance progress in the field of flexor semiconductor device fabrication. The main advantage of our fabrication procedure is it improves the electric current by current stabilate of the devices under deformation. Prepare a DUB silicon on insulator sample.This sample is ready for silicon isolation in subsequent steps. This is a schematic representation of its layer structure. Gray represents silicon, green, silicon dioxide.Red and blue are N-plus and P-plus doped regions, respectively. Spin coat a positive photoresist layer on the sample at 4, 000 rpm for 40 seconds. Next, take the sample to a hot plate to soft bake it at 90 degrees Celsius for 90 seconds.After the soft bake, take the sample to an ultraviolet photolithography set-up. There, apply a mask to the sample for 10 seconds. Retrieve the sample to develop it.Do this by immersing it in developer for one minute. Then the clean the sample in deionized water, and dry it with the nitrogen blow-gun. Next, hard bake the sample at 110 degrees Celsius for five minutes.This diagram represents the sample's layers at this point. Move on to dry-edge the sample with an inductively-coupled, plasma-reactive ion etcher for six minutes. When done, the sample has this structure.The next step is to remove the buried oxide layer. To do this, prepare a 49%solution of hydrofluoric acid. Dip the samples in it for two minutes to remove the buried oxide layer.After the acid bath, followed by cleaning and drying, the silicon isolation is complete. The next step involves plasma-enhanced chemical vapor deposition. Over two minutes, deposit a 130 nanometer silicon dioxide sacrificial layer on the sample.Spin-coat positive photoresist on the sample, followed by a soft bake. Employ a photolithography mask and expose the sample to UV light for 10 seconds. This is a representation of the sample after it is developed, and hard baked at 110 degrees Celsius for five minutes.Prepare a container of buffered oxide etch, and immerse the sample in it for 30 seconds. After cleaning and drying, the result is the partial removal of the CVD oxide layer. Deposit polyimide by spin coating it on the sample.Transfer it to a hotplate to begin annealing it at 110 degrees Celsius for three minutes, then at 150 degrees Celsius for 10 minutes. Then, move the sample to an oven with a nitrogen atmosphere, and continue to anneal it at 230 degrees Celsius for 60 minutes. Polyimide layer covers the sample, and provides a surface for a silicon dioxide sacrificial layer.Continue by depositing a 130 nanometer silicon dioxide layer with plasma-enhanced chemical vapor deposition for two minutes. Use positive photoresist to apply a mask, with 10 seconds of UV light, then develop. Perform a soft and hard bake.Form a hard mask by immersing the sample in buffered oxide etch for 30 seconds, followed by cleaning and drying it. Next, dry edge the polyimide using reaction ion etch for 20 minutes. Remove the oxide layer with buffered oxide etch, then clean and dry the sample.Now, take the sample to a sputterer to deposit chromium and gold. After that, spin coat positive photoresist before applying a photolithography mask. This sample has been developed for one minute, and hard baked at 110 degrees Celsius for five minutes.Etch the chromium and gold layers with a wet etchant for 20 seconds, to bring the sample to this state. After chromium and gold wet etching, take care when removing the photoresist, otherwise the gold may peel off. The second polyimide layer deposition and the second metallization steps proceed exactly as the first.Spin coat and anneal the second layer of polyimide to produce layers such as in this diagram. Deposit and pattern a silicon oxide layer as a hard mask layer for dry etching. Next, sputter coat 20 nanometers of chromium and 200 nanometers of gold before patterning it.Begin by adding another spin coated layer of polyimide and annealing it. Use plasma-enhanced chemical vapor deposition to deposit a 650 nanometer silicon dioxide layer over eight minutes. After spin coating positive photoresist on the sample, apply a mask with UV photolithography.Develop the sample, hard bake it, and pattern the silicon dioxide by immersing it in buffered oxide etch. Use reactive ion etching to dry etch the polyimide for 75 minutes, then dry etch the silicon for six minutes with inductively-coupled, plasma-reactive ion etching. It is now time to etch the oxide sacrificial layer.Immerse the sample in 49%hydrofluoric acid for 20 minutes. Retrieve, rinse, and dry the sample before proceeding. When you are etching the sacrificial layer with hydrofluoric acid, it is important to monitor the etching progress.Ensure your course, the device may peel off. Now, hold the sample with carbon tape applied to the substrate. Then attach water soluble tape to the patterned side.Next, strip off the water soluble tape in an instant. This prevents the device from remaining on the substrate. Get degassed PDMS in a 10-to-1 mixture prepolymer to curing agent.Also, obtain PET film sufficient to cover the sample. Spin coat the film with the PDMS at 1, 000 rpm for 30 seconds. Follow this by baking the film on a hotplate at 110 degrees Celsius for 10 minutes.When this is done, get the sample on the water soluble tape and expose it to UV light for 30 seconds. Now, work with both the sample and the film. Attach the water soluble tape with the sample to the PDMS coated PET film.With a pipette, carefully drop water on the water soluble tape to remove it from the film. Employ a slow flow of water to sweep away the water soluble tape. Finally, hold the sample with forceps, and dry it with a nitrogen blow gun.This is the phototransistor array before being transferred to a PET film. It consists of repeating phototransistor cells depicted in this image. The polyimide encapsulated serpentine electrodes allow the device to stretch.Here's the device after transfer onto a PDMS coated PET film. To measure the IV characteristics under different conditions, use a set-up similar to this. Note the definition of the radius of curvature.These are measurements of the IV characteristics of the phototransistor array, with different radii of curvature. The electrical features of the array are independent of the radius of curvature. This plot is of the ratio of the photocurrent to the dark current, as a function of voltage, for different radii of curvature.The dynamic range is about 600 or more above a bias voltage of two volts. The inset has plots of the dark current at the tested curvature extremes. Its low value causes the high dynamic range.Once mastered, this technique can be done in 48 hours, if it is performed properly. While attempting this procedure, it is important to avoid any acts that can peel the electrodes off of its substrate. Following this procedure, other methods, like polymer etching with other gases, can be performed to task, if they can be used under different conditions than those used in dry etching.After its development, this technique paved the way for researchers in the field of flexible devices to explore bio-inspired image attempts. After watching this video, you should have a good understanding of how to manufacture a flexible semi-conductor device. Don't forget that working with the necessary reagents can be extremely hazardous, and precautions, such as using masks, hoods, and headgear at your station, should always be taken while performing this procedure.

fabrication-flexible-image-sensor-based-on-lateral-nipin

Research

JoVE Journal

Engineering

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

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

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

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

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling immensely. However, in soft electronics, in which organic semiconductors play a critical role, the devices will be bent or folded repeatedly. The effect of bending on the crystal packing and thus the charge transport is crucial to the performance of the device. In this manuscript, we describe the protocol to bend a single crystal of 5,7,12,16-tetrachloro-6,13-diazapentacene (TCDAP) in the field-effect transistor configuration and to obtain reproducible I-V characteristics upon bending the crystal. The results show that bending a field-effect transistor prepared on a flexible substrate results in nearly reversible yet opposite trends in charge mobility, depending on the bending direction. The mobility increases when the device is bent toward the top gate/dielectric layer (upward, compressive state) and decreases when bent toward the crystal/substrate side (downward, tensile state). The effect of bending curvature was also observed, with greater mobility change resulting from higher bending curvature. It is suggested that the intermolecular &#960;-&#960; distance changes upon bending, thereby influencing the electronic coupling and the subsequent carrier transport ability.

This manuscript describes the bending process of an organic single crystal-based field-effect transistor to maintain a functioning device for electronic property measurement. The results suggest that bending causes changes in the molecular spacing in the crystal and thus in the charge hopping rate, which is important in flexible electronics.

The charge transport in an organic semiconductor depends highly on the molecular packing in the crystal, which influences the electronic coupling ...

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 ...

A Fabrication and Measurement Method for a Flexible Ferroelectric Element Based on Van Der Waals Heteroepitaxy

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on high-density data storage and low-power consumption capabilities. However, the high-quality oxide based nonvolatile memory on flexible substrates is often constrained by the material characteristics and the inevitable high-temperature fabrication process. In this paper, a protocol is proposed to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica. The versatile deposition technique and measurement method enable the fabrication of flexible yet single-crystalline non-volatile memory elements necessary for the next generation of smart devices.

In this paper, we present a protocol to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica.

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on ...

Fabrication and Design of Wood-Based High-Performance Composites

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber reinforced composites, due to its excellent mechanical properties. Delignified wood, however, is rather fragile in a wet state, which makes handling and shaping challenging. Here we present two fabrication processes, closed-mold densification and vacuum densification, to produce high-performance cellulose composites based on delignified wood, including an assessment of their advantages and limitations. Further, we suggest strategies for how the composites can be re-used or decomposed at the end-of-life cycle. Closed-mold densification has the advantage that no elaborate lab equipment is needed. Simple screw clamps or a press can be used for densification. We recommend this method for small parts with simple geometries and large radii of curvature. Vacuum densification in an open-mold process is suitable for larger objects and complex geometries, including small radii of curvature. Compared to the closed-mold process, the open-mold vacuum approach only needs the manufacture of a single mold cavity.

Delignified densified wood represents a new promising lightweight, high-performance and bio-based material with great potential to partially substitute natural fiber reinforced- or glass fiber reinforced composites in the future. We here present two versatile fabrication routes and demonstrate the possibility to create complex composite parts.

Delignified densified wood is a new promising and sustainable material that possesses the potential to replace synthetic materials, such as glass fiber ...

Fabrication of Surface Acoustic Wave Devices on Lithium Niobate

Manipulation of fluids and particles by acoustic actuation at small scale is aiding the rapid growth of lab-on-a-chip applications. Megahertz-order surface acoustic wave (SAW) devices generate enormous accelerations on their surface, up to 108 m/s2, in turn responsible for many of the observed effects that have come to define acoustofluidics: acoustic streaming and acoustic radiation forces. These effects have been used for particle, cell, and fluid handling at the microscale&#8212;and even at the nanoscale. In this paper we explicitly demonstrate two major fabrication methods of SAW devices on lithium niobate: the details of lift-off and wet etching techniques are described step-by-step. Representative results for the electrode pattern deposited on the substrate as well as the performance of SAW generated on the surface are displayed in detail. Fabrication tricks and troubleshooting are covered as well. This procedure offers a practical protocol for high frequency SAW device fabrication and integration for future microfluidics applications.

Two fabrication techniques, lift-off and wet etching, are described in producing interdigital electrode transducers upon a piezoelectric substrate, lithium niobate, widely used to generate surface acoustic waves now finding broad utility in micro to nanoscale fluidics. The as-produced electrodes are shown to efficiently induce megahertz order Rayleigh surface acoustic waves.&#160;

Manipulation of fluids and particles by acoustic actuation at small scale is aiding the rapid growth of lab-on-a-chip applications. Megahertz-order ...

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different materials show variability in resistive switching properties due to the intrinsic nature of the material used, leading to discrepancies in the field because of underlying operation mechanisms. This highlights a need for a reliable technique to understand mechanisms using nanostructural observations. This protocol explains a detailed process and methodology of in&#160;situ nanostructural analysis as a result of electrical biasing using transmission electron microscopy (TEM). It provides visual and reliable evidence of underlying nanostructural changes in real time memory operations. Also included is the methodology of fabrication and electrical characterizations for asymmetric crossbar structures incorporating amorphous vanadium oxide. The protocol explained here for vanadium oxide films can be easily extended to any other materials in a metal-dielectric-metal sandwiched structure. Resistive switching crossbars are predicted to serve the programmable logic and neuromorphic circuits for next-generation memory devices, given the understanding of the operation mechanisms. This protocol reveals the switching mechanism in a reliable, timely, and cost-effective way in any type of resistive switching materials, and thereby predicts the device&#39;s applicability.

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Presented here is a protocol for analyzing nanostructural changes during in&#160;situ biasing with transmission electron microscopy (TEM) for a stacked metal-insulator-metal structure. It has significant applications in resistive switching crossbars for the next generation of programmable logic circuits and neuromimicking hardware, to reveal their underlying operation mechanisms and practical applicability.

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different ...

Fabrication of a Fabry-P&#233;rot Etalon for Application in Trace-Gas Spectroscopy

Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are used for their high sensitivity as well as their exceptional filtering capability. However, air-spaced etalons with high finesse are usually built by specialized facilities. Their production requires a clean room, special glass handling, and coating machinery, meaning commercially available FPEs are sold for a high price. In this article, a new and cost-effective method to fabricate fiber-coupled FPEs with standard photonic laboratory equipment is presented. The protocol should serve as a step-by-step guide for the construction and characterization of these FPEs. We hope this&#160;will enable researchers to conduct fast and cost-effective prototyping of FPEs for various fields of application. The FPE, as presented here, is used for spectroscopic applications. As shown in the representative results section via proof of principle measurements of water vapor in ambient air, this FPE has a finesse of 15, which is sufficient for the photothermal detection of trace concentrations of gases.

Author Spotlight: Fabrication of a Low-Cost, Fiber-Coupled, and Air-Spaced Fabry-P&#233;rot Etalon  

This protocol describes the construction of a low-cost, discrete, fiber-coupled, and air-spaced Fabry-Perot etalon with various applications, such as in trace-gas spectroscopy. The fabrication is possible in any facility with standard optical laboratory equipment available.

Fabry-P&#233;rot etalons (FPE) have found their way into many applications. In fields such as spectroscopy, telecommunications, and astronomy, FPEs are ...

Microfluidic Channel-Based Soft Electrodes for Capacitive Pressure Sensing

Microfluidic Channel-Based Soft Electrodes and Their Application in Capacitive Pressure Sensing

Flexible and stretchable electrodes are essential components in soft artificial sensory systems. Despite recent advances in flexible electronics, most electrodes are either restricted by the patterning resolution or the capability of inkjet printing with high-viscosity super-elastic materials. In this paper, we present a simple strategy to fabricate microchannel-based stretchable composite electrodes, which can be achieved by scraping elastic conductive polymer composites (ECPCs) into lithographically embossed microfluidic channels. The ECPCs were prepared by a volatile solvent evaporation method, which achieves a uniform dispersion of carbon nanotubes (CNTs) in a polydimethylsiloxane (PDMS) matrix. Compared to conventional fabrication methods, the proposed technique can facilitate the rapid fabrication of well-defined stretchable electrodes with high-viscosity slurry. Since the electrodes in this work were made up of all-elastomeric materials, strong interlinks can be formed between the ECPCs-based electrodes and the PDMS-based substrate at the interfaces of the microchannel walls, which allows the electrodes to exhibit mechanical robustness under high tensile strains. In addition, the mechanical-electric response of the electrodes was also systematically studied. Finally, a soft pressure sensor was developed by combining a dielectric silicone foam and an interdigitated electrodes (IDE) layer, and this demonstrated great potential for pressure sensors in soft robotic tactile sensing applications.

Author Spotlight: Microfluidic Channel-Based Soft Electrodes and Their Application in Capacitive Pressure Sensing  

Flexible electrodes have a wide range of applications in soft robotics and wearable electronics. The present protocol demonstrates a new strategy to fabricate highly stretchable electrodes with high resolution via lithographically defined microfluidic channels, which paves the way for future high-performance soft pressure sensors.

Flexible and stretchable electrodes are essential components in soft artificial sensory systems. Despite recent advances in flexible electronics, most ...

Revolutionizing Stroke Rehabilitation with Enhanced Grasping and Finger Recovery

A Flexible Wearable Supernumerary Robotic Limb for Chronic Stroke Patients

In this study, we present a flexible wearable supernumerary robotic limb that helps chronic stroke patients with finger rehabilitation and grasping movements. The design of this innovative limb draws inspiration from bending pneumatic muscles and the unique characteristics of an elephant's trunk tip. It places a strong emphasis on crucial factors such as lightweight construction, safety, compliance, waterproofing, and achieving a high output-to-weight/pressure ratio. The proposed structure enables the robotic limb to perform both envelope and fingertip grasping. Human-robot interaction is facilitated through a flexible bending sensor, detecting the wearer's finger movements and connecting them to motion control via a threshold segmentation method. Additionally, the system is portable for versatile daily use. To validate the effectiveness of this innovation, real-world experiments involving six chronic stroke patients and three healthy volunteers were conducted. The feedback received through questionnaires indicates that the designed mechanism holds immense promise in assisting chronic stroke patients with their daily grasping activities, potentially improving their quality of life and rehabilitation outcomes.

Author Spotlight: Enhancing Grasping Abilities for Hemiplegic Patients with Flexible Robotic Limbs 

This protocol introduces a flexible wearable supernumerary robotic limb tailored to assist in finger rehabilitation for stroke patients. The design incorporates a bending sensor to facilitate seamless human-robot interaction. Validation through experiments involving both healthy volunteers and stroke patients underscores the efficacy and dependability of the proposed study.

In this study, we present a flexible wearable supernumerary robotic limb that helps chronic stroke patients with finger rehabilitation and grasping ...