Noise Mitigation Techniques for Carbon Nanotube-Based Piezoresistive Sensor Systems

Abstract

Carbon nanotube (CNT)-based piezoresistive strain sensors have the potential to outperform traditional silicon-based piezoresistors in MEMS devices due to their high strain sensitivity. However, the resolution of CNT-based piezoresistive sensors is currently limited by excessive 1/f or flicker noise. In this paper we will demonstrate several noise mitigation techniques that can be used to decrease noise in the CNT-based sensor system without reducing the sensor's strain sensitivity. First, the CNTs were placed in a parallel resistor network to increase the total number of charge carriers in the sensor system. By carefully selecting the types of CNTs used in the sensor system and by correctly designing the system it is possible to reduce the noise in the sensor system without reducing sensitivity. The CNTs were also coated with aluminum oxide to help protect the CNTs from environmental variations. Finally, the CNTs were annealed to improve contact resistance and to remove adsorbates from the CNT sidewall. Overall, using these noise mitigation techniques it is possible to reduce the total noise in the sensor system by almost two orders of magnitude and increase the dynamic range of the sensors by 29 dB.

A multi-axis MEMS sensor with integrated carbon nanotube-based piezoresistors for nanonewton level force metrology

“…However, more work still needs to be done in order to maximize the dynamic range of these sensors. Further improvements in the performance of the CNT-based can be achieved using the design optimization procedures described in [13] and the manufacturing optimization procedures described in [39]. For example, the dynamic range of the force sensor can be improved by redesigning the force sensor system to increase the sensor area.…”

Nanomanufacturing Methods for the Reduction of Noise in Carbon Nanotube-Based Piezoresistive Sensor Systems

“…Carbon nanotube-based piezoresistive strain sensors have the potential to outperform many traditional MEMS force and displacement sensors due to their high strain sensitivity [3]. However, CNT-based sensors typically suffer from large amounts of flicker noise which limits the resolution of these sensors [4,5]. Flicker noise is believed to be caused by the capture and release of charge carriers in localized trap states in the CNT [6].…”