Fabrication and characteristics of micro-electro-mechanical-system-based tilt sensor

A miniaturized tilt sensor using air medium, which is measurable on a two-axis inclination angle, is fabricated and its output characteristics are evaluated. The proposed tilt sensor consists of a central microheater surrounded by four temperature sensors. Without an inclination, the microheater creates a symmetric temperature profile in an encapsulated microchamber filled with air medium. When the device is tilted, the temperature sensors formed around the central heater measure the asymmetric temperature profile, caused by the effect of convection. The proposed tilt sensor covers a measurement range of ±90° on two axes with excellent linearity and symmetric sensitivity. Furthermore, the structure and fabrication sequence of the proposed sensor are quite simple; that is, the microheater and temperature sensors can be simultaneously formed because they are made of the same material. Several issues, confronting the previously reported electrolytic tilt sensor, such as metal electrode corrosion, electrolyte deterioration, surface tension of the electrolyte, and difficulty in packaging, were avoided.