253 research outputs found

    Microcomputer-based artificial vision support system for real-time image processing for camera-driven visual prostheses

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    It is difficult to predict exactly what blind subjects with camera-driven visual prostheses (e.g., retinal implants) can perceive. Thus, it is prudent to offer them a wide variety of image processing filters and the capability to engage these filters repeatedly in any userdefined order to enhance their visual perception. To attain true portability, we employ a commercial off-the-shelf battery-powered general purpose Linux microprocessor platform to create the microcomputer-based artificial vision support system (µAVS^2) for real-time image processing. Truly standalone, µAVS^2 is smaller than a deck of playing cards, lightweight, fast, and equipped with USB, RS- 232 and Ethernet interfaces. Image processing filters on µAVS^2 operate in a user-defined linear sequential-loop fashion, resulting in vastly reduced memory and CPU requirements during execution. µAVS^2 imports raw video frames from a USB or IP camera, performs image processing, and issues the processed data over an outbound Internet TCP/IP or RS-232 connection to the visual prosthesis system. Hence, µAVS^2 affords users of current and future visual prostheses independent mobility and the capability to customize the visual perception generated. Additionally, µAVS^2 can easily be reconfigured for other prosthetic systems. Testing of µAVS^2 with actual retinal implant carriers is envisioned in the near future

    Wafer-Level Parylene Packaging With Integrated RF Electronics for Wireless Retinal Prostheses

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    This paper presents an embedded chip integration technology that incorporates silicon housings and flexible Parylene-based microelectromechanical systems (MEMS) devices. Accelerated-lifetime soak testing is performed in saline at elevated temperatures to study the packaging performance of Parylene C thin films. Experimental results show that the silicon chip under test is well protected by Parylene, and the lifetime of Parylenecoated metal at body temperature (37°C) is more than 60 years, indicating that Parylene C is an excellent structural and packaging material for biomedical applications. To demonstrate the proposed packaging technology, a flexible MEMS radio-frequency (RF) coil has been integrated with an RF identification (RFID) circuit die. The coil has an inductance of 16 μH with two layers of metal completely encapsulated in Parylene C, which is microfabricated using a Parylene–metal–Parylene thin-film technology. The chip is a commercially available read-only RFID chip with a typical operating frequency of 125 kHz. The functionality of the embedded chip has been tested using an RFID reader module in both air and saline, demonstrating successful power and data transmission through the MEMS coil

    Wide field epiretinal micro-electrode-design and feature test

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    This study was aimed to design and fabricate a wide field implantable epi-retinal microelectrode array for the purpose of retinal repair, and to perform electrochemical test on the array. With parylene as flexible substrate material and Pt as electrode and route material, microelectrode array prototypes was designed and fabricated, and electric characteristics of the array was tested with the three-electrode test system. The feature analysis showed that morphological and electrical properties of the array well met the requirements of implantation and electrical stimulation of retina. The microelectrode array can be put in the in vivo electrophysiological experiments on animal and can perform reliably. © 2013 IEEE.published_or_final_versio

    Implantable CMOS Biomedical Devices

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    The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented

    Data analysis of retinal recordings from multi-electrode arrays under in situ electrical stimulation

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    The development of retinal implants has become an important field of study in recent years, with increasing numbers of people falling victim to legal or physical blindness as a result of retinal damage. Important weaknesses in current retinal implants include a lack of the resolution necessary to give a patient a viable level of visual acuity, question marks over the amount of power and energy required to deliver adequate stimulation, and the removal of eye movements from the analysis of the visual scene. This thesis documents investigations by the author into a new CMOS stimulation and imaging chip with the potential to overcome these difficulties. An overview is given of the testing and characterisation of the componments incorporated in the device to mimic the normal functioning of the human retina. Its application to in situ experimental studies of frog retina is also described, as well as how the data gathered from these experiments enables the optimisation of the geometry of the electrode array through which the device will interface with the retina. Such optimisation is important as the deposit of excess electrical charge and energy can lead to detrimental medical side effects. Avoidance of such side effects is crucial to the realisation of the next generation of retinal implants
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