Updated on 17 September 2013
Again, body-worn monitors require low power, a small size, and no compromise on performance. Analog Devices' AD8232 heart rate monitor (HRM) analog front end (AFE) effectively acquires bio-potential signals while maintaining low power usage and low cost. Key features include leads-off detection, fast restore, right leg drive, and a flexible architecture that enables the configuration of external filters to help reduce the effects of motion artifacts. Operating off a single supply at 175 μA (typ), the AD8232 HRM AFE simplifies the development process.
Sports and fitness
One of the fastest growing market sectors for health monitoring is sports and fitness. The two categories of monitoring are fitness and safety. Traditionally, fitness management has been performed using heart rate monitoring devices in the form of a chest strap or in the handle bars of a treadmill machine. Electrode-based heart rate monitoring remains a popular approach to recording cardiac output. What is changing, however, is the way electrodes are formed. For instance, new textile technologies that use conductive material in the weave of the fabric enable larger surface areas on the body to pick up the bio-potential signals.
Optical devices that detect photoplethysmograph (PPG) signals offer another method for measuring heart rate. A PPG device, typically worn on the wrist, uses the ulnar artery to detect blood flow and hence, determine heart rate. This method is used in a number of monitoring devices targeting athletes.
Other vital signs that contribute to the determination of energy exertion, calorie burn, and general fitness level include:
• Activity monitoring (low power MEMS accelerometer)
• Respiration monitoring (thoracic impedance- or MEMs-based)
• Perspiration measurement (skin impedance)
• Temperature (surface flux and core)
When it comes to sports safety, concussion ranks as one of the highest sports-related injuries. As we learn more about the long term effects of repeated concussions, from high school through amateur sports to the professional games, the call for technology to help detect the severity of a head impact is increasing. Where to locate the impact sensor is a challenge. For many sports the problem is easily solved - MEMS inertial sensors can be placed in the helmet to detect impact from multiple locations. In the case of car racing, MEMS inertial sensors are placed in driver earpieces. However, not all impact sports require helmets or head gear. For those athletes, concussion-level impact is being detected and measured using impact sensors embedded in mouth guards.