ERGO S.A., with 160 employees, is a Greek Commercial-Marketing Company that imports, manufactures and distributes medical equipment and medical devices along with medical disposables.
The major part of the company turnover comes by representing of foreign Companies.
The company’s main product is the Artificial Kidney Machine (Haemodialysis Unit) which has proven to be a highly commercially successful product. The patient’s dependence on the machine calls for a high reliability of the machine and elimination of errors.
The former product was based on standard IC components and two microprocessors (MPU1 and MPU2). In the old system, the two microprocessors (MPU1 and MPU2) control the rest of system circuits and are able to detect wrong status in these circuits. The communication between two processors was only one way : MPU2 Ë MPU1. The MPU2 cooperated with analog circuits (sensor modules) and safety relays and was responsible to send the safe information to the MPU1. Its role was to detect if the values of the main parameters are out of range (arterial pressure, venous pressure, speed of arterial and venous pump), and to inform the MPU1. Then the MPU1, as the main microprocessor, enabled the protective system (the electromechanical relay) and stopped the motor power supply. The blood pumps stopped and it was possible to operate the blood pumps manually, so that the extracorporeal blood would return safely to the patient.
If one of the two microprocessors was out of order (froze), there was no way of determining it accurately in order to generate an alarm signal for the machine’s user (just the machine had to be restarted like after RESET). There was no external watchdog timer for the both microprocessors simultaneously (the part of controlling of MPU1 had the MPU2). In this situation one supervisor (ASIC chip!) was necessary to control the good working status of them. A mixed-signal ASIC was developed, to perform a lot of control functions and replace a number of discrete components (there were external ADCs, therefore the ASIC is used also as ADC). More specifically, the ASIC has the role of interfacing among the peripheral devices (e.g. sensors) and the two independent microprocessor units, to control the monitor displayed information, as well as determining the accuracy of operations and generating an alarm signal in case of failure.
The payback period is about 3 years from the end of the experiment, as CE mark approval date for the product is estimated to be at the end of 2000. So time to market is going to be early in 2001. ROI is 6 times the initial investment over a 5-year period. The actual project’s duration was 17 months, with an actual effort of 23,5 person-months. Funding from E.C. was 90 KECUs and was not exceeded.
The application experiment is of interest to any company specialising in medical devices where increased safety and reliability are crucial factors.
