
269Mechanical Nanosensors
resistance (consistently increasing and never decreasing in value) with pres-
sure was observed. For larger pressures, there was a non-monotonic anom-
aly. However, the piezoresistive gauge factor of the metallic SWCNT = 200 ± 8,
slightly exceeded the value of doped-Si strain gauge (200).
4.13 Tunnel Effect Accelerometer
4.13.1 Principle of Motion Detection
As already explained in Section 1.19, the STM is a displacement nanosen-
sor utilizing the extreme sensitivity of tunneling current to variations in
electrode spacing. Several methods have been developed for implementa-
tion of position sensors based on