Session: MNS-01-02: Dynamics of MEMS/NEMS 2nd Session

Paper Number: 95319

95319 - Frequency-Dependent Photothermal Forcing of Afm Microcantilevers 

We study the low-frequency vibrational response of a gold-coated AFM microcantilever as a function of modulation frequency and spot location of a photothermal heating laser. A bilayer cantilever undergoes flexural bending due to differences in the coefficients of thermal expansion of the constituent materials.  The frequency-dependent bending response of the cantilever is experimentally observed within an AFM system.  For comparison, a one-dimensional coupled thermomechanics and heat transfer model of a photothermally-actuated AFM cantilever is implemented. At low frequency, the frequency-dependent bending response of the cantilever is constant.  Past a critical frequency, the bending response decreases with increasing modulation frequency.  Our results show that in the low-frequency limit the optimized photothermal laser spot position is near the free end of the cantilever as opposed to near the cantilever base. Additionally, we extract the cantilever’s thermal time constant by fitting the frequency-dependent bending response of the cantilever.   We observe an increase in thermal time constant as the photothermal laser spot is moved toward the free end of the cantilever. In the low-frequency limit, the implemented model underpredicts the bending response compared to experiments by up to 90 %.  This underprediction may be related to neglecting cantilever bending contributed by the through-thickness temperature variation in the cantilever.   Our results illustrate different aspects of the frequency-dependent photothermal laser spot optimization that can guide users to maximizing cantilever response to a given input power.

Presenting Author: Akshay Deolia Purdue University

Presenting Author Biography: I’m a Ph.D. student working in Prof. Arvind Raman’s Multiphysics Vibrations lab. I started at Purdue in Spring 2021 and am co-advised by Prof. Raman and Prof. Ryan B Wagner. <br/>My current research interests include heat transfer-induced vibrations and dynamics at the nano and macro scales. I’m further interested in exploring micro/nano dynamics through the use of atomic force microscopy to solve interdisciplinary research problems during the course of my Ph.D.

Authors:

Akshay Deolia Purdue University
Ryan Wagner Purdue University
Arvind Raman Purdue University