Ultra-low power operation of self-heated, suspended carbon nanotube gas sensors

Abstract

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.

Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensors

“…Self-heating effects have also been proven in individual carbon nanotubes operated with a few W [15,43]. In this work, we used carbon nanofibers [44] (from now on CNFs), a carbon allotrope offering characteristics and sensing capabilities [41,45] comparable to carbon nanotubes and graphene [46] at a much lower production cost.…”

“…Specifically, self-heating was first proven in one single SnO 2 nanowire, obtaining reliable devices operated with less than 10 W [18][19][20][21][22]. To the best of our knowledge, self-heating has further been studied in sensor devices with highly ordered nanostructures, such as suspended nanowires [15,19,20], or catalytically activated materials [17]. All these studies involved complex fabrication steps and laboratory fabrication methods hardly transferable to a higher production scale, hampering the widespread application of this promising approach.…”

“…In the third case, sensor active layer functionalization [9,10], material decoration [11,12] and the use of hybrid materials [11,13,14] are traditional strategies to enhance and modify the active film properties, and hence the gas-surface interaction mechanism. In one way or another, state of the art gas sensors still require more than 10-100 mW (research devices) to maintain the elevated temperatures for good sensing performance, which limits their use in mobile distributed systems [15].…”

Effect of varying gate distance on the threshold voltage shift in carbon nanotube field effect transistor gas sensors

“…Nevertheless, the required voltage range to perform a full gate sweep and acquire a complete transistor characteristic spans a range of several tens of volts [15][16][17]. This large voltage range however is not compatible with ultra-low power bias and read-out circuits [19][20][21][22][23] and would render the ultra-low power argument for these materials void.…”

“…When building CNT sensors with a suspended channel [14], hysteresis and drift [15] as well as the power consumption [16] can be significantly reduced.…”