Project Focus

This project focuses on the design of micro-pillars with focus on understanding adhesion and tractive properties. Understanding such key mechanics allows for tuning these pillars and micro-patterned surfaces for multiple applications from in vivo surgical robotics, to cell manipulation. Collaborators on this project have included Dr. Kurt Maute (CU-Boulder Aerospace Engineering Sciences) and Dr. Rong Long (CU-Boulder Mechanical Engineering). Project funding and recent peer-reviewed papers are listed below.

Three-Dimensional Microscale Imaging and Measurement of Soft Material Contact Interfaces Under Quasi-Static Normal Indentation and ShearLangmuir. (AbstractPDF)

Mechanics of Materials (2020): Friction Between a Plane Strain Circular Indenter and a Thick Poroelastic Substrate

Abstract: This paper presents a computational study on the role of poroelasticity in gel friction. Motivated by recent experimental studies in the literature, we develop a plane strain finite element model to elucidate the contact mechanics between a circular indenter and a thick poroelastic substrate under both normal and shear...

Langmuir (2019): Three-Dimensional Microscale Imaging and Measurement of Soft Material Contact Interfaces Under Quasi-Static Normal Indentation and Shear

Abstract: Understanding the contact and friction of soft materials is vital for a wide variety of engineering applications including soft sealants and medical devices such as catheters and stents. While the mechanisms of friction between stiff materials have been extensively studied, the mechanisms of friction between soft materials are much...

Journal of the Mechanics and Physics of Solids (2019): Delamination of a Rigid Punch from an Elastic Substrate Under Normal and Shear Forces

Abstract: Delamination of rigid objects from an elastic substrate with finite thickness is a fundamental problem underlying applications such as marine fouling release coatings or anti-icing coatings. Most existing theoretical studies assume that delamination is driven by forces normal to the substrate surface, while in practice the delamination force may...

Mechanics of Materials (2018): A Representative Volume Element Model for the Adhesion Between a Micro-Pillared Surface and a Compliant Substrate

Abstract: A representative volume element (RVE) model was developed to understand how the adhesion response between an effectively rigid substrate with micro-pillar arrays and a compliant substrate is affected by the spacing and aspect ratio of pillars. A number of verification and validation steps were taken to ensure the RVE...

Langmuir (2017): Characterizing Adhesion between a Micro-Patterned Surface and a Soft Synthetic Tissue

Abstract: The work of adhesion and work of separation are characteristic properties of a contact interface that describe the amount of energy per unit area required to adhere or separate two contacting substrates, respectively. In this work, the authors present experimental and data analysis procedures that allow the contact interface...

IEEE/ASME Transactions on Mechatronics (2015): An Automated Traction Measurement Platform and Empirical Model for Evaluation of Rolling Micro-Patterned Wheels

Abstract: Colonoscopy is the leading preventative procedure for colorectal cancer. The traditional tool used for this procedure is an endoscope, which can cause patient discomfort, pain and fear of the procedure. There has been a movement to develop a robotic capsule colonoscope (RCC) in an attempt to mitigate these drawbacks...

Journal of Mechanical Behavior of Biomedical Materials (2014): Soft Material Adhesion Characterization for In vivo Locomotion of Robotic Capsule Endoscopes: Experimental and Modeling Results

Abstract: The objective of this work is to validate an experimental method and nondimensional model for characterizing the normal adhesive response between a polyvinyl chloride based synthetic biological tissue substrate and a flat, cylindrical probe with a smooth polydimethylsiloxane (PDMS) surface. The adhesion response is a critical mobility design parameter...

Tribology Letters (2013): Preliminary Friction Force Measurements on Small Bowel Lumen when Eliminating Sled Edge Effects

Abstract: This study aims to produce experimental results for the coefficient of friction (COF) between the small bowel lumen and an edgeless, translating sled. Friction was measured as a function of sled speed under in situ and in vitro conditions. The results indicate that by eliminating edge effects, the COF...

Tribology International (2013): A Tribological Investigation of the Small Bowel Lumen Surface

Abstract: Robotic capsule endoscopy (RCE), where a robotically controlled capsule endoscope is used to navigate the gastrointestinal tract, is a developing technology currently hindered by mobility challenges within the small bowel. This research seeks to engage the frictional characterization of the small bowel with a formally designed experiment which samples...

IEEE Transactions on Biomedical Engineering (2012): The Design and Characterization of a Testing Platform for Quantitative Evaluation of Tread Performance on Multiple Biological Substrates

Abstract: In this study, an experimental platform is developed to quantitatively measure the performance of robotic wheel treads in a dynamic environment. The platform imposes a dynamic driving condition for a single robot wheel, where the wheel is rotated on a translating substrate, thereby inducing slip. The normal force of...

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