A biosensor is any piece of hardware that interacts with a biological or physiological system to acquire a signal for either diagnostic or therapeutic purposes. Data gathered using biosensors are then processed using biomedical signal processing techniques as a first step toward facilitating human or automated interpretation.
The body sends out very weak electrical signals, which must somehow be captured and converted into information that can be used by a healthcare worker. With the development of the EKG, for example, engineers managed to isolate a very small and noisy signal polluted by other signals from the body to provide a real-time display of the activity of the heart.
In the area of imaging, the strong magnetic field used by MRIs prohibits the use of anything metal in conjunction with this valuable diagnostic tool. So biomedical engineers have developed MRI-compatible electrodes and other instrumentation that allows, say, a patient with epilepsy to be monitored for changes in EEG activity during an MRI.
The Phone Oximeter
Given the concerns about the costs of healthcare, particularly in developing nations, low-cost alternatives to traditional monitoring equipment and machines are being sought. Rather than purpose-built physical boxes, the power of the cell phone is being used to both monitor and transmit biomedical signals.
Pulse oximetry is used to monitor blood oxygen levels; particularly in settings where anesthesia is administered. Researchers at the University of British Columbia are taking advantage of the computing power, real-time wireless communication and low cost of smart phones to provide pulse oximetry outside the hospital setting.
Biosensor technology incorporates a wide range of devices, from the basic stethoscope, thermometer and blood pressure cuff to sophisticated PET scanners, MRI and ultrasound machines.
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