PhD Defense announcement

Yiching Liang yiching at
Wed May 30 22:38:42 PDT 2001

Title: Piezoresistive Cantilevers for Force Measurements

Yiching Liang
Department of Mechanical Engineering, Stanford University
Ph.D. Defense

Monday, June 4, 2001. 11:00 AM
Refreshments at 10:45 AM
Location: Packard Auditorium (Packard 101)

Atomic Force Microscopy (AFM) has been used extensively for imaging
surface topography to atomic resolution. In addition to imaging
applications, AFM cantilevers are also effective instruments for measuring
very small forces. Piezoresistive AFM, which uses cantilevers with
integrated piezoresistive sensors, has become an attractive alternative to
the more popular optical AFM because of its ease of use and scalability.
Force measurements can provide important information for studying various
physical phenomena. This includes physical forces such as friction and
surface adhesion, and biological processes such as cellular adhesion,
antibody-antigen binding, molecular mechanics, protein folding, and
large-scale animal biomechanics. This work focuses on the development of
piezoresistive cantilevers as force sensors. Several design and
optimization techniques will be used to show that piezoresistive AFM can
achieve resolution comparable to that of an optical AFM. Ultra-thin n-type
piezoresistive cantilevers were fabricated and characterized to show
significant performance improvement over previous work. Noise
characteristics and how they relate to optimization will also be
discussed. Finally, a particular force measurement is described where
piezoresistive cantilevers are used to measure the van der Waals adhesion
properties of individual gecko setae.

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