GALCIT Colloquium

The adhesion of soft elastomers, such as polydimethylsiloxane (PDMS), is important in a broad range of applications, including microtransfer printing, soft robots, and bioinspired adhesives. In this talk I will discuss the control of elastomer adhesion in two related studies: (1) characterization of rate-dependent PDMS adhesion during contact and separation using a blister contact test, and (2) a novel approach for structuring surfaces to achieve adhesion tuning via loading direction.

In the first part, measurements of the rate-dependent adhesion of PDMS with a blister contact test will be discussed. A unique feature of these measurements is that the adhesion is measured during both contact formation and separation. Rate is shown to have a significant impact on the effective adhesion energy during both contact formation and separation. The results have implications for controlling adhesion and contact area in manufacturing processes, such as microtransfer printing.

The second part of the talk will describe a new approach to realize tunable adhesion. While there has been significant effort in creating micro- and nano-structured surfaces that have tunable adhesion, many of the surfaces rely on structures with complex geometries to achieve the desired adhesion characteristics.  Here, we present a different approach to realize strong and tunable adhesion through the use of surfaces comprised of composite pillars. The composite pillars lead to surfaces that have strong adhesion under normal loading and weak adhesion in shear.  This behavior has been demonstrated through experimental studies and mechanics modeling. These composite surfaces have applications pick-and-place manufacturing processes as well as robotic gripping.