We present a suspended carbon nanotube gas sensor that senses NO2 at ambient temperature and recovers from gas exposure at an extremely low power of 2.9 μW by exploiting the self-heating effect for accelerated gas desorption. The recovery time of 10 min is two orders of magnitude faster than non-heated recovery at ambient temperature. This overcomes an important bottleneck for the practical application of carbon nanotube gas sensors. Furthermore, the method is easy to implement in sensor systems and requires no additional components, paving the way for ultra-low power, compact, and highly sensitive gas sensors.

No abstract

No abstract

No abstract

We present the design, fabrication, and characterization of an in-plane vibration sensor with frequency selective displacement amplification and differential capacitive read-out. The mechanical structure is based on six resonators with decreasing stiffness coupled in-plane. A differential capacitance attached to the last mass serves as electrical read out. Finite element and lumped element models are both presented. The devices were fabricated in a single mask silicon on insulatorbased process. The mechanical, as well as the capacitive transfer function and the pressure dependence, have been investigated experimentally and compared with simulations. The measured mean (minimum) amplification was 24 dB (16 dB) over a bandwidth of 10 kHz (3-13 kHz). While the mean amplification is pressure dependent, the minimum amplification and bandwidth show a less than 10% decrease over a wide pressure range from 6.3 to 64 mbar. The pressure dependent measurements also show that the minimum amplification is independent of the Q factor of the modes down to values of Q∼10. Both simulation and experiment show that the off-axis modes occur outside the bandwidth of the device. Along with the low cross-sensitivity of the capacitive readout (0.06%), this provides good axis selectivity despite the high number of degrees of freedom. The device can be used for detection of broadband vibration signals, e.g., for structural monitoring of infrastructure such as bridges and pipelines.