Semiconducting metal oxide (SMO) gas sensors were designed, fabricated, and characterized in terms of their sensing capability and the thermo-mechanical behavior of the micro-hotplate. The sensors demonstrate high sensitivity at low concentrations of volatile organic compounds (VOCs) at a low power consumption of 10.5 mW. In addition, the sensors realize fast response and recovery times of 20 s and 2.3 min, respectively. To further improve the baseline stability and sensing response characteristics at low power consumption, a novel sensor is conceived of and proposed. Tantalum aluminum (TaAl) is used as a microheater, whereas Pt-doped SnO2 is used as a thin film sensing layer. Both layers were deposited on top of a porous silicon nitride membrane. In this paper, two designs are characterized by simulations and experimental measurements, and the results are comparatively reported. Simultaneously, the impact of a heat pulsing mode and rubber smartphone cases on the sensing performance of the gas sensor are highlighted.

This paper presents design, fabrication, and characterization of a novel microelectromechanical microreed switch, which consists of two Ni₈₀Fe₂₀ magnetic plates as microreeds. One is embedded in a silicon trench. The other is suspended above the substrate and supported by a pair of crab-leg flexures from the two sides. Both Ni₈₀Fe₂₀ plates are split into two long, narrow strips to improve the sensitivity. The switch is actuated by bringing an external magnet closer to the switch. The magnetic field required to turn on the switch can be as low as 0.5 mT and the initial contact resistance is <; 10 Ω with gold contacts. The switch has been tested to pass more than 40 million hot switching cycles at 2 mA current at room temperature when packaged at wafer level with SU-8 sealing. The die size is 1.7 × 1.8 × 1.1 mm³. The proposed microreed switch can be used as the proximity sensor to sense the magnetic field. It also has the potential to replace the conventional reed switch in portable electronics, such as cellular phones, hearing aids, and laptops, where conserving battery power and device size is critical.

A passive MEMS magnetostatic relay using only one electroplated magnetic layer was presented. The relay consists of an electroplated Ni 80 Fe 20 plate supported by a pair of torsion bars from two sides. The relay is actuated by approaching an external magnet to the relay. The switching-on magnetic field is about 4.8 mT and the contact resistance is about 3 ohms with gold contact. The lifetime testing shows more than 7.5 million hot switching cycles with 1-2 mA current. This passive magnetic relay could find applications in portable electronics, such as cellular phones, personal data assistant (PDA), pace makers, hearing aids, etc.

A passive magnetostatic microelectromechanical systems (MEMS) switch using only one electroplated soft magnetic layer of nickel-iron (Ni80Fe20) alloy was designed, fabricated, and characterized. The switch is composed of an electroplated Ni80Fe20 plate supported by a pair of torsion bars from two sides. The Ni80Fe20 plate is patterned into long and narrow strips to improve the sensitivity. The switch is actuated by bringing an external magnet closer to the switch. Therefore, no internal electrical power is consumed by the device for actuation. The magnetic field required to turn on the switch is 4.8 mT, and the initial contact resistance is 0.5 Ω with gold contacts. The switch has been tested to pass more than 34 million hot-switching cycles at 2-mA current at room temperature when packaged at the wafer level with SU-8 sealing. The die size is 2.1 × 1.94 × 1.1 mm3. The magnetic switch of this paper has the potential to replace the conventional reed switch in portable electronics such as laptops, cellular phones, personal data assistants, pacemakers, and hearing aids.

Semiconducting metal oxide (SMO) gas sensors, dedicated to wearable devices were designed, fabricated, and characterized in terms of power consumption, thermal distribution, and sensing capability. The sensors demonstrate a sensitivity down to ppb-level VOC concentrations at a low power consumption of 10.5 mW. To further enhance the baseline stability and sensing response characteristics at low power consumption, a new sensor structure is proposed. The design implements novel aspects in terms of fabrication and microheater geometry, leading to improved sensor performance which enables new applications for SMO gas sensors. In this work, two designs were analyzed using experimental characterization and simulation. The results of the analyses of the two sensors are comparatively reported.

This paper presents the design, the fabrication and the characterization of a novel MEMS micro-reed switch, which consists of two Ni ₈₀ Fe ₂₀ magnetic plates as micro-reeds. One is embedded in a silicon trench. The other is suspended above the substrate and supported by a pair of crab-leg flexures from the two sides. Both Ni ₈₀ Fe ₂₀ plates are split into two long, narrow strips to improve the sensitivity. The switch is actuated by bringing an external magnet closer to the switch. The magnetic field required to turn on the switch can be as low as 1 mT. The contact force is estimated to ~20 μN and the initial contact-resistance is <;10 Ω with gold contacts. The switch has been tested to pass more than 40 million hot switching cycles at 2 mA current at room temperature when packaged at wafer level with SU-8 sealing. The die size is 1.7×1.8×1.1 mm ³ . The proposed micro-reed switch can be used as the proximity sensor to sense the magnetic field. It also has the potential to replace the conventional reed switch in portable electronics, such as cellular phones, hearing aids and laptops, where conserving battery power and device size is critical.