Spatial Thermal Gradient Mapping Micro-Machined Accelerometer Arrays
Spatial thermal gradient mapping in micro-machined accelerometer arrays decouples linear motion from external board heat using differential thermopile matrices.
Convection Micro-Cavity
Thermal Environment
Sealed enclosures house micro-electromechanical systems to create a controlled fluid environment for heat-based sensing. Inside a convection micro-cavity, the movement of gas allows for the detection of acceleration or inclination without a solid proof mass. This design avoids the mechanical stiction and fatigue associated with traditional silicon beams.
Fluid Dynamics
Heat sources within the chamber create a localized bubble of warm gas. As the device moves, the convection micro-cavity experiences a shift in the position of this thermal bubble relative to internal temperature sensors. This displacement is proportional to the external force applied to the package.
The density of the gas and the power supplied to the heater determine the sensitivity of the sensor output.
Interference Source
External temperature gradients affect the internal flow patterns and introduce measurement errors. If the convection micro-cavity is not properly insulated, the drift in the zero-point reading becomes excessive. Manufacturers often use secondary temperature sensors to provide a compensation signal for these environmental changes.
Packaging Standard
Hermetic sealing prevents moisture from entering the chamber and altering the gas composition. Water vapor changes the thermal conductivity of the internal gas, which alters the calibration of the convection micro-cavity. Maintaining a dry inert gas fill is necessary for the long-term stability of the device.