Integrated circuit technology significantly improves the performance of microelectromechanical systems (MEMS)
Integrated circuit technology significantly improves the performance of microelectromechanical systems (MEMS)
MEMS (Micro-Electro-Mechanical Systems) sensors are highly sought after in the motion, acceleration, tilt, and vibration measurement markets. MEMS sensors offer system-in-package solutions with advantages such as high resolution, low power consumption, and compact size.
MEMS differs significantly from semiconductor chips that primarily utilize the electrical properties of silicon. The core component of a MEMS lacks the gate-drain-source triode; instead, it is a miniature mechanical structure made entirely of silicon. A typical MEMS structure includes a mass-motor slider, a spring, and a damper, operating on a principle essentially the same as a mass-spring model.
MEMS sensors can add an intuitive human-machine interface to mobile phones, MP3/MP4 players, PDAs, or game console controllers, enabling interaction between human actions and the device with the MEMS sensor.
In household appliances such as washing machines and dryers, MEMS accelerometers can also act as vibration detectors. When the load inside the machine becomes unbalanced, the washing machine will alert the user, preventing premature wear and tear before malfunctions occur.
Single-axis and dual-axis accelerometers are widely used in automotive passive safety systems, such as front and side airbags. Accelerometers and gyroscopes are also used in navigation systems and active safety systems, such as ABS braking systems and wheel stability control systems.
In recent years, MEMS sensors have seen a trend towards "consumer electronics." MEMS sensors have begun to penetrate the consumer electronics market to solve various application problems.
Consumer electronics manufacturers are looking for miniaturized, inexpensive, low-voltage, and low-power MEMS sensors. Slim designs are a trend in battery-powered products such as mobile phones, MP3 and MP4 players, and portable PCs. Moreover, multi-axis sensors have become an essential feature of consumer electronics devices, allowing consumers to activate any function from any physical location. In portable products, there is still no fixed reference framework for MEMS sensor applications.
Furthermore, the lifecycle of consumer electronics products is becoming increasingly shorter, so product designers require MEMS to be quickly and seamlessly integrated into end applications.
STMicroelectronics, at the forefront of MEMS technology development, has begun integrating multiple sensors—accelerometers, gyroscopes, and magnetometers—into a single package. This solution enhances the functionality and performance of various applications, including motion monitoring. Integrated sensors enable autonomous and automated systems that monitor specific conditions and translate them into actions with little or no user intervention.
In portable mobile devices such as smartphones, game consoles, and personal navigation systems, a sensor capable of accurately measuring angular rates along three orthogonal axes can achieve 360° angular rate detection, enabling high-precision recognition of 3D gestures and movements. Furthermore, a 3-axis accelerometer paired with a gyroscope allows designers to develop inertial measurement units (IMUs) that track the motion type, speed, and direction of people, vehicles, and other objects, providing comprehensive information.
STMicroelectronics' accelerometers incorporate many enhanced features, including single-click and double-click recognition, motion detection/wake-up, and 4D/6D orientation detection. Other key features include a programmable FIFO (First-In, First-Out) buffer and two programmable interrupt signal output pins to immediately notify the main processor of motion detection, single-click/double-click events, and other conditions.
Integrating a compass module into a mobile phone to provide advanced location-related services has sparked an application revolution in the mobile phone market. With compass and GPS functionality, consumers can simply point their phones at nearby service facilities, such as hotels or shopping malls, to identify and search for relevant target information.
Combining motion detection with magnetometry enhances the mobile user experience in several ways. Application developers can effectively address the challenge of viewing maps on phones or PDAs with limited screen size by placing the user's current location at the bottom of the map and displaying the direction of travel (directly above) on the rest of the screen, providing accurate navigation information. It can also indicate the direction of travel for a person or vehicle when there is no GPS signal. This solution also supports dead reckoning applications, including walking navigation in areas with no or weak GPS signals, such as when walking in tall buildings or densely forested mountainous environments.
STMicroelectronics has integrated a 3-axis digital accelerometer and a 3-axis digital magnetometer into its LSM303DLH module. This digital compass combines high accuracy, small size, and low power consumption to meet the growing market demand for advanced navigation capabilities and emerging smart positioning services. STMicroelectronics' high-performance system-in-package digital compass utilizes Honeywell's magnetoresistive technology to facilitate the application of enhanced electronic compass functionality in portable consumer electronics devices. Compass functions include orientation lookup, map/direction display, location services, and walking direction estimation. The product's linear acceleration measurement range is ±2/±4/±8g, and its magnetic field strength measurement range is ±1.3 to ±8 Gauss, both user-selectable ranges.
Many technology and business experts believe that wireless sensor networks, home robots, smart pills, and lab-on-a-chip represent the next commercial opportunity for MEMS sensors. Examples include lab-on-a-chip for personalized medicine development and tire pressure monitoring systems consisting of a 5-node wireless pressure sensor network.
STMicroelectronics' MEMS experts are currently focusing on developing smart sensors. These 'smart sensors' integrate MEMS devices and processors within a single package, allowing them to run sensor algorithms independently without the need for a main processor. This reduces system-level power consumption, which is crucial for power-hungry handheld devices.
