The main aim of this textbook is to provide the tools to understand the function and design of different biomedical instruments and devices, and for the reader to be able to use these tools to envision new and improved future technology and designs. Throughout the book the terms medical and biomedical are used interchangeably, and similarly with the terms device and instrument. With several thousand instruments and devices on the market it is clearly impossible to consider more than a handful in detail. Instead, this book concentrates on the following general approach.
(i) What is the clinically relevant measurement that needs to be made?
(ii) What are the pathophysiological mechanisms that give rise to the clinical condition?
(iii) What are the characteristics (e.g. magnitude, frequency, bandwidth) of the signal to be measured? How accurate and reproducible does the measurement have to be? What are the interfering signals that have to be suppressed?
(iv) What are the recommended instrumental specifications for the particular device? How does one design the device to meet these specifications?
(v) How does one test the biocompatibility and electrical safety of such a device, whether it is external or implanted, so that it can operate safely for a number of years?
Traditionally, most of these instruments and devices have been located in a hospital, and patients travel to the clinics for the measurements to be performed by trained personnel. However, this model is changing and nowadays there is an increasing role for what is termed mobile health (m-health), which involves a much greater degree of healthcare being performed by the patients themselves at home. This means that a biomedical device must operate in the patient's home environment without specialized training, as well as transmit the data wirelessly and securely to the physician. This model of continuous patient monitoring not only provides a much more complete assessment of the patient's health, but also reduces the number of visits that a patient has to make to the hospital.
The main areas of technological development that have enabled the rapid incorporation of m-health into the healthcare infrastructure are wearable and implantable devices that can transmit data to the physician via mobile phone networks.