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Wearable, Luminescent Oxygen Sensor for Transcutaneous Oxygen Monitoring
摘要: We present a new concept for a wearable oxygen (O2) sensor for transcutaneous O2 pressure (tcpO2) monitoring by combining the technologies of luminescent gas sensing and wearable devices. O2 monitoring has been exhaustively studied given its central role in diagnosing various diseases. The ability to quantify the physiological distribution and real-time dynamics of O2 from subcellular to the macroscopic level is required to fully understand mechanisms associated with both normal physiological and pathological conditions. Despite its profound biological and clinical importance, few effective methods exist for noninvasively quantifying O2 in a physiological setting. The wearable sensor developed here consists of three components: a luminescent sensing film attached onto skin by a carbon tape, an organic light-emitting diode (OLED) as a light source, and an organic photodiode (OPD) as a light detector. All the components are solution-processable and integrated on a plane in a bandage-like configuration. To verify the performance, tcpO2 variations by pressure-induced occlusion were measured in the lower arm and a thumb by the wearable sensor, and the results were comparable to those measured by a commercial instrument. In addition to its flexibility, other features of this sensor render it a potential low-cost solution for the simultaneous monitoring of tcpO2 in any part of a body.
关键词: organic light-emitting diodes,transcutaneous oxygen monitoring,wearable sensors,luminescent oxygen sensing,organic photodiodes
更新于2025-09-23 15:21:21
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Vein detection with near-infrared organic photodetectors for biometric authentication
摘要: We combine a low dark current and high-detectivity near-infrared (NIR)-sensitive organic photodetector with a high-resolution 508 pixels per inch (ppi) oxide thin-film transistor (TFT) backplane to create a large-area thin NIR detector, using processes that are compatible with flat-panel display fabrication. The detector is characterized showing high uniformity and linearity. With the use of a NIR light source, the detector is capable of imaging the (pattern of) veins under the skin in reflection, leading to improved biometric authentication.
关键词: near-infrared organic photodiodes,vein detection,biometric authentication,large-area photodetector arrays
更新于2025-09-23 15:21:01
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Higha??Accuracy Photoplethysmography Array Using Neara??Infrared Organic Photodiodes with Ultralow Dark Current
摘要: Reflectance oximeters based on organic photodiode (OPD) arrays offer the potential to map blood pulsation and oxygenation via photoplethysmography (PPG) over a large area and beyond the traditional sensing locations. Here, an organic reflectance PPG array based on 16 × 16 OPD pixels is developed. The individual pixels exhibit near-infrared sensitivity up to ≈950 nm and low dark current density in the order of 10?6 mA cm?2. This results in high-quality PPG signals. Analysis of the full PPG waveform yields insight on the artery stiffness and the quality of blood circulation, demonstrating the potential of these arrays beyond pulse oximetry and heart-rate calculation.
关键词: photoplethysmography,organic photodiodes,bulk heterojunction,heartbeat,pulse oximetry
更新于2025-09-23 15:19:57
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Bifunctional Etalon-Electrode to Realize High Performance Color Filter Free Image Sensor
摘要: Organic photodiodes (OPDs), based on organic semiconductors with high absorption coefficients for visible light, are emerging as potential candidates for replacing silicon photodiodes in image sensors, particularly due to the possibility of realizing a thin thickness and exclusion of color filters, both of which can contribute to a dramatically enhanced degree of integration for image sensors. Despite years of research, techniques have not yet been developed that allow the OPD itself to have color selectivity while maintaining a thin (<1 μm) OPD thickness, in combination with a sufficiently high detectivity (>1012 cm?Hz0.5/W). To solve this issue, we introduce a concept of 'etalon-electrode', which can perform the function of electrode, and simultaneously the function of selective wavelength transparency. A strategically designed OPD architecture consisting of an etalon-electrode, a panchromatic organic active layer, and a counter electrode displays well-defined narrowband R-/G-/B-selective detectivity spectra depending on precision-adjusted thickness composition of the etalon-electrode. While a thin thickness of OPD is preserved at less than 800 nm including electrodes, active layer and other buffer layers for all R-/G-/B-selective OPDs, high average detectivity values over 1012 cm?Hz0.5/W are demonstrated. Furthermore, the characteristic of imparting color selectivity by the etalon-electrode enables a more facile full color patterning, such that a prototype of a 10×10 image sensor with a pixel pitch of 500 μm is realized, resulting in accurate picturing of a well-defined full color image.
关键词: high detectivity,organic photodiodes,etalon-electrodes,full-color imaging,color filter free,image sensor,wavelength selectivity
更新于2025-09-19 17:15:36
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Pulse Oximetry Using Organic Optoelectronics under Ambient Light
摘要: Light absorption in oxygenated and deoxygenated blood varies appreciably over the visible and near-infrared spectrum. Pulse oximeters use two distinct wavelengths of light to measure oxygen saturation SpO2 of blood. Currently, light-emitting diodes (LEDs) are used in oximeters, which need additional components to drive them and negatively impact the overall size of the sensor. In this work, an ambient light oximeter (ALO) is demonstrated, which can measure photoplethysmography signals and SpO2 using various kinds of ambient light, avoiding the use of LEDs. Spectral filters are combined with organic photodiodes to create the ALO with sensitivity peaks at green (525 nm), red (610 nm), and near-infrared (740 nm) wavelengths. Finally, the wearable ALO is used to measure photoplethysmography signals and SpO2 on the index finger in different indoor and outdoor lighting conditions and the measurements are validated with commercial pulse oximeters under normal and ischemic conditions.
关键词: photoplethysmography,organic photodiodes,oximeters,flexible electronics,wearable sensors
更新于2025-09-16 10:30:52
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Near‐infrared organic photoelectric materials for light‐harvesting systems: Organic photovoltaics and organic photodiodes
摘要: The inherent advantages of organic optoelectronic materials endow light-harvesting systems, including organic photovoltaics (OPVs) and organic photodiodes (OPDs), with multiple advantages, such as low-cost manufacturing, light weight, flexibility, and applicability to large-area fabrication, make them promising competitors with their inorganic counterparts. Among them, near-infrared (NIR) organic optoelectronic materials occupy a special position and have become the subject of extensive research in both academia and industry. The introduction of NIR materials into OPVs extends the absorption spectrum range, thereby enhancing the photon-harvesting ability of the devices, due to which they have been widely used for the construction of semitransparent solar cells with single-junction or tandem architectures. NIR photodiodes have tremendous potential in industrial, military, and scientific applications, such as remote control of smart electronic devices, chemical/biological sensing, environmental monitoring, optical communication, and so forth. These practical and potential applications have stimulated the development of NIR photoelectric materials, which in turn has given impetus to innovation in light-harvesting systems. In this review, we summarize the common molecular design strategies of NIR photoelectric materials and enumerate their applications in OPVs and OPDs.
关键词: organic photodiodes,near infrared,organic optoelectronic materials,organic photovoltaics
更新于2025-09-12 10:27:22
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A High‐Performance Solution‐Processed Organic Photodetector for Near‐Infrared Sensing
摘要: Sensitive detection of near-infrared (NIR) light enables many important applications in both research and industry. Current organic photodetectors suffer from low NIR sensitivity typically due to early absorption cutoff, low responsivity, and/or large dark/noise current under bias. Herein, organic photodetectors based on a novel ultranarrow-bandgap nonfullerene acceptor, CO1-4Cl, are presented, showcasing a remarkable responsivity over 0.5 A W?1 in the NIR spectral region (920–960 nm), which is the highest among organic photodiodes. By effectively delaying the onset of the space charge limited current and suppressing the shunt leakage current, the optimized devices show a large specific detectivity around 1012 Jones for NIR spectral region up to 1010 nm, close to that of a commercial Si photodiode. The presented photodetectors can also be integrated in photoplethysmography for real-time heart-rate monitoring, suggesting its potential for practical applications.
关键词: high responsivity,bulk heterojunctions,photodetectors,organic photodiodes,near-infrared
更新于2025-09-12 10:27:22
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Highly flexible and solution-processed organic photodiodes and their application to optical luminescent oxygen sensors
摘要: We present a solution-processed flexible organic photodiode (f-OPD) with a bulk heterojunction (BHJ) structure based on a blend of poly (3-hexylthiophene-2,5-diyl) and 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (P3HT:PCBM). We used Cs2CO3-doped polyethyleneimine ethoxylated (d-PEIE) as the electron transport layer (ETL) material, which significantly improved the electron injection properties of the f-OPD. Compared with f-OPDs with conventional ETL materials such as Cs2CO3, the external quantum efficiency (EQE) of the d-PEIE-based f-OPD was highly improved. Analytical results showed that the d-PEIE reduced the work function of the cathode, thereby facilitating the efficiency of electron injection from the active layer (AL) to the cathode of the f-OPD. In addition, after 10,000 cycles of tensile bending at a bending radius of 5 mm, the normalized ID variation (ID/ID0) in the d-PEIE-based f-OPD remained above 90%, indicating an excellent device bending stability. Finally, f-OPD-based luminescent oxygen (O2) sensors were successfully fabricated consisting of a photoluminescent O2 sensing film, a light source, and an f-OPD. The O2 sensors based on d-PEIE-based f-OPDs showed the highest photocurrent and O2 sensitivity in relation to the O2 concentration compared with O2 sensors based on f-OPDs with conventional ETL materials.
关键词: organic photodiodes,electron transport layer,Cs2CO3,polyethyleneimine ethoxylated
更新于2025-09-10 09:29:36