We have fabricated a force sensor using carbon nanotubes (CNTs) as a sensing element which directly synthesized on silicon micro structure. Generally, electrical resistance of the CNT increases when its length changes from its original length. We measured the electrical resistance change of the CNTs to detect the force applied on the CNTs. We fabricated Si beam structure on top silicon layer of the SOI wafer. The CNTs were directly synthesized between the Si beam and the bottom Si layer (bridging CNTs) by chemical vapor deposition (CVD). After we synthesized bridging CNTs on the structure, we infiltrated and cured the PDMS prepolymer solution (polydimethylsiloxane) on the surface of the beam structure and the bridging CNTs, so that we can detect force without any damage to the sensing element. As a result, the electrical resistance of the bridging CNTs changes by 3.2% for a 4.9 N force applied on the beam. In conclusion, the electrical resistance of the bridging CNTs increases according to the force applied on the beam, and our proposed force sensor can detect a force.

References :
Yusuke Takei, Kiyoshi Matsumoto, Isao Shimoyama, “Force Sensor Using Carbon Nanotubes Directry Synthesized on Micro Structure,” 20th IEEE International Conference on Micro Electro Mechanical Systems (MEMS '07), pp. 827-830, Kobe, Japan, Jan. 21-25, 2007. Proceedings