MEMs motion sensors are commonly used in consumer applications like smartphones, tablets, gaming devices, remote control (gesture recognition and pointing), notebooks, ultrabooks, and cameras. MEMS is also used in fitness and wellness applications like athlete performance monitoring, watches and PND, treadmills, and even barbells. Well, without our knowledge, they are even on our home appliances, cars, and hospital equipments, even industrial plants rely on them.
Medical or hospital equipments nowadays need to be accurate and precise especially for critical condition equipments. Cardio-Pulmonary Resuscitation (CPR), Magnetic Resonance Imaging (MRI), Computerized Tomography Scan (CT Scan), and others alike need to be accurate and precise in order to have a better result. Technological advances in hospital equipments. Accurately determining position of imaging and scanning equipments and precise repetition rate of CPRs can save so many lives with minimal to zero fatality.
Complex Motion Requires Precision Sensors and Embedded Sensor Processing
While simple motion detection, linear movement along one axis, for example, is valuable to a number of applications, such as detecting whether an elderly person has fallen, a majority of applications involve multiple types and multiple axes of motion. Being able to capture this complex, multidimensional motion can enable new benefits while maintaining accuracy in the most critical of environments. In many cases, it is necessary to combine multiple sensor types—linear and rotational, for instance—in order to precisely determine the motion an object has experienced. As an example, accelerometers are sensitive to the Earth’s gravity, so they can be used to determine inclination angle. As a MEMS accelerometer is rotated through a ±1-g field,(±90°), it is able to translate that motion into an angle representation. However, the accelerometer cannot distinguish static acceleration (gravity) from dynamic acceleration. In the later case, an accelerometer can be combined with a gyroscope, and post-processing of both devices can discern the linear acceleration from the tilt,based upon known motion dynamics models. This process of sensor fusion obviously becomes more complex as the system dynamics (number of axes of motion, types, and degrees of freedom of motion) increase. It is also important to understand the environmental influences on sensor accuracy. Temperature is obviously a key concern and can typically be corrected for; in fact, higher precision pre-calibrated sensors will dynamically compensate themselves. A less obvious factor to consider is the potential for even slight vibrations to produce accuracy shifts in rotational rate sensors. These effects, known as linear acceleration and vibration rectification, can be significant depending on the quality of the gyroscope. Sensor fusion improves performance by using an accelerometer to detect linear acceleration and compensate for the gyroscope’s linear acceleration sensitivity.
For many applications, particularly those requiring performance beyond basic pointing (up, down, left, right) or simple movement (in motion or stationary), multiple degrees-of-freedom motion detection is required. For example, a six degree-of-freedom inertial sensor has the ability to detect linear acceleration on each of three (x, y, z) axes and rotational movement on the same three axis, also referred to as roll, pitch, and yaw, as depicted in Figure 2.
Enabling High Value Medical Applications with Precision MEMs Sensors
MEMS inertial sensing is a highly mature technology in terms of both commercial viability and reliability. Beyond the well known use cases in mobile devices and gaming, significantly more challenging needs exist in the medical and industrial fields. In these cases, substantially higher performance is required, along with much more complete integration and sensor processing. The complexity of motion involved in medical navigation, for instance, dictates the need for starting with highly stable inertial sensors as a foundation, then building on this with optimized integration, sensor processing, and fusion. The availability of highly accurate and environmentally robust sensor developments is driving a new surge in the adoption of MEMS inertial sensors within the medical field. These inertial MEMS devices are capable of offering advantages in precision, size, power, redundancy, and accessibility over existing measurement/sensing approaches. Fortunately, many of the principles required for solving these next-generation medical challenges are based on proven approaches from classical industrial navigation problems, including sensor fusion and processing techniques.
To learn more about the MEMS Enable Medical Innovation, click on the link below:
http://www.eeweb.com/company-blog/mouser/mems-enable-medical-innovation/
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