Stretchable colour-sensitive quantum dot nanocomposites for shape-tunable multiplexed phototransistor arrays

Jang

et al. 2022

Gels

Self Cite

Organic electrochemical transistors (OECTs) have become popular due to their advantages of a lower operating voltage and higher transconductance compared with conventional silicon transistors. However, current OECT platform-based skin-inspired electronics applications are limited due to the lack of stretchability in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Some meaningful structural design strategies to resolve this limitation, including rendering OECT to make it more stretchable, have been reported. However, these strategies require complicated fabrication processes and face challenges due to the low areal density of active devices because wavy interconnect parts account for a large area. Nevertheless, there have been only a few reports of fully deformable OECT having skin-like mechanical properties and deformability. In this study, we fabricated stretchable and conductivity-enhanced channel materials using a spray-coating method after a composite solution preparation by blending PEDOT:PSS with several ionic liquids. Among these, the PEDOT composite prepared using 1-butyl-3-methylimidazolium octyl sulfate exhibited a better maximum transconductance value (~0.3 mS) than the other ion composites. When this material was used for our deformable OECT platform using stretchable Au nanomembrane electrodes on an elastomer substrate and an encapsulation layer, our d-ECT showed a barely degraded resistance value between the source and drain during 1000 cycles of a 30% repeated strain. We expect that our d-ECT device will serve as a step toward the development of more precise and accurate biomedical healthcare monitoring systems.

Section: Methodsmentioning

confidence: 99%

PEDOT Composite with Ionic Liquid and Its Application to Deformable Electrochemical Transistors

Jang

et al. 2022

Gels

Self Cite

“…Semiconducting nanoparticles have been widely used in optoelectronic devices (e.g., image sensors , and displays − ) owing to their facile processability and excellent optical characteristics (e.g., high color purity and high quantum efficiency). , Semiconducting nanoparticles can be coated as a thin film via low-temperature solution-based processes (Figure a), allowing integration with other functional nanomaterials (e.g., AOSs and 2D materials). , These semiconducting nanomaterials have diverse form factors ranging from 0D (i.e., quantum dots (QD)) to 3D bulk. Among these, QDs have attracted significant attention because of their size-dependent characteristics arising from the quantum confinement effect. , For example, the bandgap of QDs can be precisely tuned by engineering the degree of confinement within the range of exciton Bohr radii (2–20 nm) .…”

Section: Nanomaterial-based Synaptic Optoelectronic Devicesmentioning

confidence: 99%

“…Type-II heterostructures of semiconducting nanoparticles and adjacent functional nanomaterials have also been used in synaptic optoelectronic devices because slow charge transfer at their heterojunction leads to synaptic photoresponses. , A large amount of EHPs are generated in the semiconducting nanoparticles when irradiated with light (Figure c). , Then, the generated electrons and holes drift in opposite directions owing to the band offset formed in the type-II heterostructure . Electrons and holes accumulate at each material across the interface, increasing the photoconductivity (Figure d). , Such charge transfer is energetically favorable for type-II band alignment but still requires high activation energy.…”

Section: Nanomaterial-based Synaptic Optoelectronic Devicesmentioning

confidence: 99%

“…Semiconducting nanoparticles have been widely used in optoelectronic devices (e.g., image sensors 78 , 79 and displays 80 − 82 ) owing to their facile processability and excellent optical characteristics (e.g., high color purity and high quantum efficiency). 83 , 84 Semiconducting nanoparticles can be coated as a thin film via low-temperature solution-based processes ( Figure 4 a), allowing integration with other functional nanomaterials (e.g., AOSs and 2D materials).…”

Section: Nanomaterial-based Synaptic Optoelectronic Devicesmentioning

confidence: 99%

See 1 more Smart Citation

Nanomaterial-Based Synaptic Optoelectronic Devices for In-Sensor Preprocessing of Image Data

et al. 2023

Self Cite

With the advance in information technologies involving machine vision applications, the demand for energy- and time-efficient acquisition, transfer, and processing of a large amount of image data has rapidly increased. However, current architectures of the machine vision system have inherent limitations in terms of power consumption and data latency owing to the physical isolation of image sensors and processors. Meanwhile, synaptic optoelectronic devices that exhibit photoresponse similar to the behaviors of the human synapse enable in-sensor preprocessing, which makes the front-end part of the image recognition process more efficient. Herein, we review recent progress in the development of synaptic optoelectronic devices using functional nanomaterials and their unique interfacial characteristics. First, we provide an overview of representative functional nanomaterials and device configurations for the synaptic optoelectronic devices. Then, we discuss the underlying physics of each nanomaterial in the synaptic optoelectronic device and explain related device characteristics that allow for the in-sensor preprocessing. We also discuss advantages achieved by the application of the synaptic optoelectronic devices to image preprocessing, such as contrast enhancement and image filtering. Finally, we conclude this review and present a short prospect.

“…However, commercial HR detection devices are intrinsically uncomfortable to wear and prevent the user's natural motion range introducing more motion artifacts due to their rigid form and lack of conformal contact with the skin 20 . Further, the inherent manufacturing complexity of epidermal electronics, specifically electrode fabrication 21,22 , has been a critical factor in preventing mass manufacture. Thus, an easily customizable low-cost electrode fabrication has been introduced utilizing a high-resolution micromachining tool.…”

Section: Introductionmentioning

confidence: 99%

Soft wearable flexible bioelectronics integrated with an ankle-foot exoskeleton for estimation of metabolic costs and physical effort

Kim

Kantharaju

et al. 2023

npj Flex Electron

Activities and physical effort have been commonly estimated using a metabolic rate through indirect calorimetry to capture breath information. The physical effort represents the work hardness used to optimize wearable robotic systems. Thus, personalization and rapid optimization of the effort are critical. Although respirometry is the gold standard for estimating metabolic costs, this method requires a heavy, bulky, and rigid system, limiting the system’s field deployability. Here, this paper reports a soft, flexible bioelectronic system that integrates a wearable ankle-foot exoskeleton, used to estimate metabolic costs and physical effort, demonstrating the potential for real-time wearable robot adjustments based on biofeedback. Data from a set of activities, including walking, running, and squatting with the biopatch and exoskeleton, determines the relationship between metabolic costs and heart rate variability root mean square of successive differences (HRV-RMSSD) (R = −0.758). Collectively, the exoskeleton-integrated wearable system shows potential to develop a field-deployable exoskeleton platform that can measure wireless real-time physiological signals.