Live long and prosper

Of all the engineering breakthroughs, those in the medical field are probably the ones that, from day to day, we least realise exist but are the ones we are most thankful for when we need them. Among the various innovations out there is Electrocardiography (ECG). Always an essential prop in any hospital drama, it is essential for patient care and is a very visual example of how sensors are being used in the medical sector. ECGs interpret the electrical activity of the heart using electrodes attached to the outer surface of the skin then record and display the data on a device external to the body. The electrodes detect and the external device amplifies the tiny electrical changes on the skin that are caused when the heart muscle depolarises during each heartbeat. At rest, each heart muscle cell has a negative charge across its outer wall. Increasing this negative charge towards zero is called depolarization, which activates the mechanisms in the cell that cause it to contract. During each heartbeat a healthy heart will have an orderly progression of a wave of depolarisation that is triggered by the cells in the sinoatrial node, which spread out through the atrium, passing through intrinsic conduction pathways and then spreading all over the ventricles. This is detected as tiny rises and falls in the voltage between two electrodes placed either side of the heart and displayed as a sine wave on a screen. The wave indicates the overall rhythm of the heart and can highlight weaknesses in different parts of the muscle. But for all their benefits, ECGs do tend to be rather intrusive. Up to 12 pads need to be stuck on to very specific areas of the body, directly on to the skin with a special gel and strong adhesive. These must then be discarded after each use. This means that patients have to wear scrubs around the hospital, have the discomfort of both the cold gel and strong adhesive being pulled off, during application and removal, and it is a physical attachment that is very restrictive to movement. Though that doesn't seem all that bad, it is the older generation who are perhaps more sensitive to these intrusions that are the highest users, and this can lead to problems and issues when monitoring. The challenge The challenge this month, then, is to come up with an improved way to monitor the heartbeats of patients in hospitals in a much less obtrusive manner. Ideally the technology should be reusable, be able to be used through clothing, not need any special gels or adhesives to work, and need limited contact with the patient. However, the data gathered needs to be as good as good – if not better – resolution than that of conventional electrodes. The solution does take advantage of recent breakthroughs in technology and eagle eyed readers may have spotted earlier articles about the technology in the magazine. However, the device is now being used commercially to excellent effect. We will publish the solution in the next issue of Eureka. In the mean time, see if you can come up with something better.