Search results for: Hiroaki Takehara
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Journal of Applied Polymer Science > 141 > 12 > n/a - n/a
The chemical and physical properties of protonated polyaniline (PANI)‐based films, including PANI‐emeraldine salt (ES) and PANI/polyvinyl acetate (PVAc) films, before and after pH treatments are characterized and compared. Protonated PANI‐based films are prepared by spin coating. The effects of pH value and immersion time on the film properties are investigated to gain a better understanding of their...
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Microfluidics and Nanofluidics > 2018 > 22 > 10 > 1-7
The application of chip-based microcapillary electrophoresis (µCE) to determine the electrophoretic mobility of molecules and particles has been intensively studied in the last two decades. Balancing the hydrostatic pressure between both ends of the microchannel is essential for free-zone electrophoresis and highly accurate measurement. This balancing operation appears simple on a macroscale (e.g...
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Proceedings of the IEEE > 2017 > 105 > 1 > 158 - 166
In this review, we present an implantable microimaging device to observe brain activities of small experimental animals such as mice and rats. Three categories of such devices are described: an optical fiber system, a head-mountable fluorescent microscope, and an ultrasmall image sensor that can be directly implanted into the brain. Among them, we focus on the third one, because this is a powerful...
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A retinal prosthesis is one of the candidate technologies to help blind patients regain their vision. Electrical stimulation of the retinal cells evokes a visual sensation such as phosphene. We have proposed retinal stimulators using a smart electrode embedded with CMOS microchips. A large-scale array, which is required for high-resolution restoration of vision, can be achieved using the smart electrode...
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In this study, we examine hemodynamic imaging by using an implantable CMOS image sensor with self-reset pixels. The self-reset function prevents saturation and allows imaging under a high light intensity condition. Thus, effective signal-to-noise ratio (SNR) over the photon shot noise limit in a normal pixel can be achieved. We designed a prototype using a 0.35-pm process. The self-reset function...
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A compact system proposed here is designed primarily for a digital enzyme-linked immunosorbent assay (ELISA). Conventional digital ELISA systems require a fluorescence microscope for counting of a fluorescent micro-reaction-chamber array with or without fluorescence in order to determine the concentration of the target proteins. Our proposed system is compact as it does not use lens optics. The system...
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CMOS-based opto-electronic neural interface devices are presented. The devices are designed with target application of in vitro and in vivo optogenetics. Two types of the opto-electronic neural interface devices are presented. One is single-chip type device for on-chip optogenetics, and the other is multi-chip type device with flexibility and wide-area coverage for in vivo optogenetics on brain. Design,...
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IEEE Design & Test > 2016 > 33 > 4 > 37 - 48
This article confirmed that the sensor retains its measurement capability for more than 150 days in a saline solution. In addition, an optimization of the sensor structure for obtaining an improved response time was carried out. A response time as short as that of the conventional self-monitoring of blood glucose (SMBG) technology was obtained with the optimized sensor structure.
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We discuss an on-chip fluorescence detection system with a microchamber array based on a CMOS image sensor. The system has three main parts: the CMOS image sensor, a light guide structure to achieve high optical coupling efficiency between the fluorescence source and the photodiode in the sensor, and a microchamber array for fluorescence-tagged reaction. In this paper, we propose three types of light...
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IEEE Transactions on Electron Devices > 2016 > 63 > 1 > 215 - 222
In this paper, we propose and demonstrate an implantable CMOS image sensor with self-resetting pixels. The self-resetting function is implemented using a four-transistor Schmitt trigger inverter. The pixel has no counter for the number of self-resets, because the application does not require radiometric (linear) response. The pixel is fabricated using the 0.35- $\mu \text{m}$ 2-poly 4-metal standard...
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The enzyme-linked immunosorbent assay (ELISA) is a diagnostic technique used for detecting the presence of viruses or tumor markers. To detect target biomarkers, antigen-antibody reactions followed by fluorescent reactions are carried out in an ELISA. Recently, digital ELISAs have been proposed to achieve higher sensitivity. In the digital ELISA, fluorescent reactions are carried out in an array of...
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A CMOS-based neural interface device with on-chip localized optical stimulation capability was proposed and demonstrated. A multifunctional CMOS image sensor with an addressable on-chip electrode array was integrated with a GaInN light emitting diode (LED) array formed on a sapphire substrate. The basic functionality of the device was evaluated, and optical stimulation on ChR2-expressed Neuro-2A cells...
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In this study, we propose an advanced architecture of a smart electrode for neural stimulation of a retinal prosthesis. A feature of the proposed architecture is embedding CMOS microchips into the core of the stimulus electrodes. Microchip integration without dead space on the array is possible. Additionally, higher durability can be expected because the microchips are protected by the stimulus electrodes...
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We have developed an implantable complementary-metal-oxide-semiconductor (CMOS) imaging device for green fluorescence imaging to observe various neural activities of the mouse brain in a freely moving state. The device comprises a CMOS image sensor, blue LEDs as excitation light sources, and absorption filters to enable real-time green fluorescence imaging. To observe weak green fluorescence reactions...
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We have developed implantable complementary -metal-oxide-semiconductor (CMOS) imaging devices for brain functional imaging (Fig.1) [1]. With the device, it is possible to perform fluorescence or absorption imaging and observe various neural activities of the mouse brain in a freely moving state [2, 3]. The device comprises a CMOS image sensor, and LEDs as excitation or illumination light sources....
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Fullerenes are expected to be one of the first carbon nanomaterials to be widely employed for various commercial applications. However, one critical factor that has limited the development of such applications is the high cost and limited availability of fullerenes. Much of this problem is due to the small-scale, batch nature of fullerene production using carbon arcs. In contrast, the combustion method...
