|The insulin pump for diabetics|
|SE 8 Web|
Diabetes is a medical condition where the body does not manufacture its own insulin. Insulin is used to metabolise sugar and, if it is not available, the person suffering from diabetes will eventually be poisoned by the build-up of sugar. It is important to maintain blood sugar levels within a safe range as high levels of blood sugar have long-term complications such as kidney damage and eye damage. These are not however, normally dangerous in the short-term.
Very low levels of blood sugar (hypoglaecemia) are potentially very dangerous in the short-term. They result in a shortage of sugar to the brain which causes confusion and ultimately a diabetic coma and death. In such circumstances, it is important for the diabetic to eat something to increase their blood sugar level.
Most diabetics are currently treated by injections of insulin 2 or 3 times a day but this leads to peaks and troughs in their level of insulin. A portable insulin pump measures the level of blood sugar at regular intervals and delivers doses of insulin depending on the actual level of sugar in the blood. This will lead to a situation where the sufferers blood sugar levels are much closer to those of people without diabetes. The complications and long-term effects of diabetes can therefore be reduced.
The system measures the level of blood sugar every 10 minutes and if this level is above a certain value and is increasing then the dose of insulin to counteract the increase is computed and injected into the diabetic. The system can also detect abnormally low levels of blood sugar and, if these occur, an alarm is sounded to warn the diabetic that they should take some action.
This case study focuses on the control software for the insulin pump which is concerned with reading the blood sugar (glucose) sensor, computing the insulin requirements and controlling the micro pump which causes the insulin to be delivered.
Use in teachingUse to illustrate various aspects of critical systems engineering
Referenced in several chapters in 'Software Engineering'