A neurostimulator application-specific integrated circuit (ASIC) with scalable circuitry that can stimulate 14 channels, has been developed for an epi-retinal vision prosthesis. This ASIC was designed to allow seven identical units to be connected to control up to 98 channels, with the ability to stimulate 14 electrodes simultaneously. The neurostimulator forms part of a vision prosthesis, designed to restore vision to patients who have lost their sight due to retinal diseases such as retinitis pigmentosa and macular degeneration. For charge balance, the neurostimulator was designed to stimulate with current sources and sinks operating together, and with the ability to drive a hexagonal mosaic of electrodes to reduce the electrical crosstalk that occurs when multiple bipolar stimulation sites are active simultaneously. A hexagonal mosaic of electrodes surrounds each stimulation site and has been shown to effectively isolate each site, increasing the ability to inject localized independent charge into multiple regions simultaneously.
We present novel circuits for high-voltage digital level shifting with zero static power consumption. The conventional topology is analysed, showing the strong dependence of speed and dynamic power on circuit area. Novel techniques are shown to circumvent this and speed up the operation of the conventional level-shifter architecture by a factor of 5-10 typically and 30-190 in the worst case. In addition, these circuits use 50% less silicon area and exhibit a factor of 20-80 lower dynamic power consumption typically. Design guidelines and equations are given to make the design robust over process corners, ensuring good production yield. The circuits were fabricated in a 0.35 m high-voltage CMOS process and verified. Due to power and IO speed limitation on the test chip, a special ring oscillator and divider structure was used to measure inherent circuit speed.
BPMN and t.BPM are sufficiently suitable for the planned modelling and imaging of CP. The application in medicine is new, and transfer from the industrial process management is in principle possible. BPMN-CP may be used for teaching and training, patient information and quality management. The graphical image is clearly structured and appealing. Even though the efficiency in the creation of BPMN-CP increases markedly after the training phase, high amounts of manpower and time are required. The most sensible and consequent application of a BPMN-CP would be the direct integration into the hospital computer system. The integration of a modelling language, such as BPMN, into the hospital computer systems could be a very sensible approach for the development of new hospital information systems in the future.
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