9‐4: Low Leakage Organic Backplanes for High Pixel Density Optical Sensors

Banach, Mike; Markham, Steve; Agaiby, Rimoon; Too, P.

doi:10.1002/sdtp.12566

Cited by 12 publications

(9 citation statements)

References 9 publications

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“…[111] Recently, many groups have succeeded in capturing fingerprints using flexible image sensors. [112][113][114][115][116][117] By combining organic transistors and printed organic photodiodes, Banach et al realized a high-resolution flexible image sensor with a pixel density of 500 dpi and a total thickness of 300 µm. [112] Their organic transistors exhibited dark current below 10 −17 A µm −1 , which was lower than amorphous silicon or polysilicon TFTs.…”

Section: Fingerprintsmentioning

confidence: 99%

“…[112][113][114][115][116][117] By combining organic transistors and printed organic photodiodes, Banach et al realized a high-resolution flexible image sensor with a pixel density of 500 dpi and a total thickness of 300 µm. [112] Their organic transistors exhibited dark current below 10 −17 A µm −1 , which was lower than amorphous silicon or polysilicon TFTs. Therefore, by using the organic TFTs as a backplane, they realized a flexible image sensor that detects light with low intensity and succeeded in capturing fingerprints (Figure 12a).…”

Section: Fingerprintsmentioning

confidence: 99%

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Recent Progress of Flexible Image Sensors for Biomedical Applications

2021

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irradiating X-rays, have become indispensable approaches for diagnosing diseases. [4] Other similar applications may include imaging based on positron emission tomography using gamma rays, [10] deep ultraviolet resonant Raman imaging of a cell, [11] histopathology images using visible light, [12] and electroencephalography through nearinfrared (NIR) light [13] (Figure 1).An image sensor, or an imager, is an essential electronic device that supports such type of bioimaging technology. Image sensors have two main components: single or multiple optical sensors (for detecting light) and circuits (for reading the output from optical sensors). Multiple optical sensors are arranged in an array with specific rows and columns. By reading light signals from the sensors using readout circuits, the spatial and/or temporal distribution-localization of biological information is determined, while its dynamics can be analyzed as an image. Two important applications of such bioimaging techniques are static imaging, which involves techniques, such as X-ray and CT, and dynamic imaging, which concerns object detection such as pulse, [14] blood oxygen levels, [15,16] and blood flow. [17] In static imaging, the imaging speed is not required as only little dynamic movements exist, but it requires high resolution and high sensitivity. Meanwhile, in dynamic imaging, high resolution is not required, but high-speed imaging is essential (Figure 2).Recently, the miniaturization of semiconductor devices has led to the development of imaging devices for wearable electronics. As a typical example, a smartwatch integrates small optical sensors that can continuously monitor biological information, such as pulse, blood pressure, and blood oxygen levels, for the long-term by simply wearing the sensors in direct contact with the skin.The flexibility of image sensors is improving to reduce the discomfort caused by such wearable electronics. Because hard and heavy devices cause relatively high discomfort, their prolonged and continuous use increases the psychological and physical burden on the user. Thus, a flexible imaging device that uses soft materials and thin substrates to reduce the device thickness and weight is an effective approach for load reduction. Further, flexible devices are easier to bend and attach to the bioplane than traditional solid devices. Consequently, problems of inaccuracy or intermittency of data acquisition caused by fluctuations in the physical distance between the target skin surface and the device can be reduced. Therefore, flexible imaging Flexible image sensors have attracted increasing attention as new imaging devices owing to their lightness, softness, and bendability. Since light can measure inside information from outside of the body, optical-imaging-based approaches, such as X-rays, are widely used for disease diagnosis in hospitals. Unlike conventional sensors, flexible image sensors are soft and can be directly attached to a curved surface, such as the skin, for continuous measurement of biometric information wi...

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Section: Fingerprintsmentioning

confidence: 99%

Section: Fingerprintsmentioning

confidence: 99%

Recent Progress of Flexible Image Sensors for Biomedical Applications

2021

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“…However, in long term, it would be a more ideal route to integrate the OPD with the organic TFT (OTFT) backplane, and thus fully exploit the advantages of organic electronics. With the rapid development of soluble organic semiconductors and their matched material stacks, the OTFT can achieve better performance figure of merits in mobility, leakage current and stability than those of the a-Si:H TFT [35][36][37]. With such all organic integration, low processing temperature and well-matching of both thermal and mechanical properties with the common plastic films are able to achieved for building ubiquitous imagers of highly customizable form factors.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Solution-Processed All Organic Integration for Large-Area and Flexible High-Resolution Imaging

Hou

Chen

Tang

et al. 2022

IEEE J. Electron Devices Soc.

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A facile blade-coating process is developed for large area deposition of uniform thick organic active layers in organic photodiodes (OPDs). Large-area semi-transparent top metal electrodes are thermally evaporated with an optimal deposition rate to achieve good balance between transparency and conductivity for top illumination integration structure with the organic thin-film transistor (OTFT) backplane. The maximum process temperature of the OPD is 85 ℃, so that the performance of the OTFT underneath is not affected. Based on the developed integration structure and processes, an all-organic integrated flexible active-matrix imager is developed, having the largest size (130 mm × 130 mm), highest resolution (1536 ×1536 pixels, 300 ppi) and lowest process temperature (100 ℃) reported so far for the OPD based imagers.

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“…Among the optical devices, a flexible organic imager that can be placed on a curved surface of the body is used in wearable electronics. Taking advantage of the flexibility, a flexible imager that can identify fingerprints or veins [3,4], a pulse meter and pulse oximeter that can be directly applied to the skin [5], and a muscle contraction sensor [6] have been reported.…”

Section: Introductionmentioning

confidence: 99%

70‐2: Sheet‐type Image Sensor with Near Infrared Sensitive Organic Photodiode

Yokota

Nakamura

Kato

et al. 2021

Symp Digest of Tech Papers

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We have developed an ultra‐flexible organic photodetector with high sensitivity in near infrared regions. The photodetector exhibits good mechanical durability. The change in dark and photocurrent was approximately 10% after 500 cycles at a bending radius of 1.6 cm. Furthermore, the photodetector also shows good air stability. By combining the organic photodetector and low‐temperature polycrystalline silicon thin‐film transistor backplane, we developed a conformable imager with a high resolution of 508 dpi.

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9‐4: Low Leakage Organic Backplanes for High Pixel Density Optical Sensors

Abstract: We present organic thin film transistors (OTFT) with leakage currents below 10 -17 A/µm and compare them to existing TFT technologies. The impact of low leakage on the dynamic range of an optical sensor was modelled to demonstrate its benefit to the performance of 500ppi device.

Cited by 12 publications

References 9 publications

Recent Progress of Flexible Image Sensors for Biomedical Applications

Recent Progress of Flexible Image Sensors for Biomedical Applications

Low-Temperature Solution-Processed All Organic Integration for Large-Area and Flexible High-Resolution Imaging

70‐2: Sheet‐type Image Sensor with Near Infrared Sensitive Organic Photodiode

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