About

Professor Robert W. Carpick is the John Henry Towne Professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. He serves as the Principal Investigator of the Carpick Research Group, which focuses on research in mechanical engineering and applied mechanics. The group includes postdoctoral researchers, doctoral students, master's students, undergraduate researchers, and high school researchers, reflecting a broad commitment to education and mentorship in the field. Professor Carpick's group has a strong history of training students and postdoctoral researchers who have gone on to diverse careers in academia, industry, and research institutions. His research group has produced numerous PhD graduates with theses covering topics such as atomic force microscopy, nanoscale friction, tribology, nanocrystalline diamond coatings, and the mechanical properties of materials at the atomic scale. The group’s work spans fundamental studies of friction, adhesion, and wear at the nanoscale, as well as applied research in materials science and engineering, including the development of next-generation contact materials for nanoelectromechanical systems and investigations into the mechanical response of metallic glasses and layered materials. Professor Carpick's leadership in the field is demonstrated by the extensive list of alumni who have become professors, researchers, engineers, and entrepreneurs, indicating his significant contributions to advancing knowledge and training in mechanical engineering and applied mechanics.

Research topics

• Materials science
• Nanotechnology
• Composite material
• Physics
• Computer Science
• Thermodynamics
• Condensed matter physics
• Optoelectronics
• Chemical physics
• Optics
• Metallurgy
• Crystallography
• Photochemistry
• Classical mechanics
• Chemistry
• Computational chemistry
• Stereochemistry
• Organic chemistry

Selected publications

• Synthetic Mucin Lubricates Interfaces at Multiple Length Scales by Stress-Induced Nanoscale Tribofilm Formation

  ACS Applied Nano Materials · 2026-02-10

  articleSenior authorCorresponding

  The tribological response of mucus is critical for organisms and in emerging applications and depends on the properties of mucins, understood to be the primary functional protein in mucus. The complexity of natural mucus makes correlating mucin structure to mucus function challenging. To address this, we study pure solutions of a synthetic mucin homopolymer, poly(Gal-Thr)22 which mimics the structure of natural mucins’ glycosylated bottlebrush domains. This permits directly correlating specific nanostructured molecular features with lubricity. For a macroscale PDMS–SiO2 contact, the boundary friction coefficient, μ, is reduced from ∼1 in pure water to <0.1 at 50 mg/mL poly(Gal-Thr)22, with more modest lubrication at lower concentrations. For a microscale PDMS–SiO2 contact measured using colloidal atomic force microscopy, which directly probes nanoscale contact mechanics, friction is also concentration-dependent: at 1 mg/mL, friction reduction vs water of 40% is attributed to reduced adhesion; at 10 and 50 mg/mL, friction reduction by 80% and 98%, respectively, is attributed to a lubricious nanoscale tribofilm that forms on the SiO2 tip. For a hard Al2O3–SiO2 microscale contact, friction falls below detection limits due to tribofilm formation under high nanoscale contact stresses. Infrared spectroscopy shows the tribofilm is a compacted structure rich in hydrogen bonds. While passively adsorbed mucin-rich films or pellicles are generally understood to provide lubricity in nature, little is known about their response to stress. Solutions of our synthetic mucin lubricate modestly when passively adsorbed, but at sufficient concentrations, with continued sliding a denser, highly lubricious tribofilm forms. Its durability permits the interface to retain lubricity when sliding in mucin-free solution. This demonstrates that a short, glycosylated homopolymer without specific surface anchoring groups substantially lubricates through stress-induced formation of an intrinsically lubricious tribofilm. This motivates further interrogation of the structure of mucins subjected to stress since until now, surface characterization in mucin lubrication studies has focused on the passively adsorbed pellicle.

  PublisherDOI

• Contact mechanics correction of activation volume in mechanochemistry

  Physical review. B./Physical review. B · 2025-05-05 · 4 citations

  articleSenior author

  Point-contact studies of interfacial chemical reactions have revealed that activation barriers can depend strongly on applied stress. However, discrepancies exist in reported values of the activation volume $\mathrm{\ensuremath{\Delta}}V$---the rate at which stress alters activation barriers---hindering its physical interpretation. We show that two contact mechanics effects---the spatially nonuniform stress, and the effect of load on reaction area---can lead to large errors. We derive a corrected model for Hertzian contacts as an example, and validate it using the growth kinetics of zinc dialkyldithiophosphate tribofilms. The model fully resolves disagreements in $\mathrm{\ensuremath{\Delta}}V$ between microscale and nanoscale atomic force microscope experiments. Our findings permit more accurate measurement of $\mathrm{\ensuremath{\Delta}}V$, which is crucial for understanding the stress-assisted thermal activation kinetics involved in mechanochemistry and tribochemistry.

  PublisherDOI

• From Auto-Kirigami to Drumheads: Suspended, Self-Tearing, and Strained Graphene Nanostructures Formed by Nanoindentation

  Langmuir · 2025-02-12 · 5 citations

  articleSenior authorCorresponding

  Nanoindentation of substrate-supported graphene can produce auto-kirigami (AK) structures: spontaneously folded and extended self-tearing nanoribbons up to several micrometers in length. However, the mechanisms governing their formation and yield are poorly understood. Here, we study graphene AK through statistical analysis of high-throughput experiments involving hundreds-fold arrays of indents on highly uniform regions of exfoliated monolayer and bilayer graphene, with no applied oscillation (in contrast with prior work). Post-mortem atomic force microscopy analysis reveals a baseline AK formation rate of 13-61% for monolayers and 0-17% for bilayers depending on inter-indent pitch. Force-distance curves of each type of nanostructure showed no appreciable differences. Moreover, graphene can remain intact after indentation, permitting formation of unbroken graphene suspended over or conformed within indents. Inter-indent pitch affects the absolute and relative formation rates of these nanostructures, attributed to indentation-induced tensile graphene strain. This advances the understanding of mechanisms for controlled formation of nanostructures, including twisted bilayers of graphene and other van der Waals materials.

  PublisherDOI

• High-Throughput Formation of 3D van der Waals Auto-Kirigami

  Nano Letters · 2025-02-28 · 1 citations

  articleCorresponding

  Two-dimensional (2D) van der Waals materials exhibit exceptional in-plane mechanical and transport properties, yet leveraging these properties in three dimensions (3D) remains a fundamental challenge. Here, we introduce a high-throughput method for the spontaneous formation of three-dimensional auto-kirigami, self-fractured and self-folded structures that evolve during indentation of thin (<100 nm) flakes of graphite and hexagonal boron nitride. These 3D structures provide direct access to in-plane properties via out-of-plane fractured surfaces, demonstrating enhanced electrical conductance along these edges. The 3D auto-kirigami consist of 2-4 plates, or "leaflets", that form by elastic buckling facilitated by in-plane fracture. By analyzing hundreds of leaflet geometries, we demonstrate that leaflet length correlates with buckling load, enabling a real-time predictor of the leaflet morphology. These 3D auto-kirigami provide a high-yield, deformation-driven platform for 3D van der Waals structures that can leverage in-plane properties of 2D materials.

  PublisherDOI

• Fracturing Graphene Steps via Atomic Force Microscopy

  Scholarly Commons (University of Pennsylvania) · 2025-09-15

  otherOpen accessSenior author

  Graphene, a 1-atom-thick sheet of carbon, has remarkable strength and flexibility, but its fracture behavior at atomic steps remains poorly understood. Graphene’s strength is weaker at its edges which can limit its performance. This project uses atomic force microscopy to characterize fracture at graphene step edges and graphene-SiO₂ edges under varying applied forces. Preliminary results indicate a positive correlation between fracture probability and normal force, though more data needs to be collected. These findings provide insight into graphene’s fracture strength and inform potential applications where its durability under stress is critical.

  Publisher

• Origin of C(1s) binding energy shifts in amorphous carbon materials

  Physical Review Materials · 2025-03-26 · 11 citations

  articleOpen access

  The quantitative evaluation of the carbon hybridization state by x-ray photoelectron spectroscopy (XPS) has been a surface-analysis problem for the last three decades due to the challenges associated with the unambiguous identification of the characteristic binding energy values for <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow><a:mi>sp</a:mi></a:mrow><a:mn>2</a:mn></a:msup></a:math>- and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msup><b:mrow><b:mi>sp</b:mi></b:mrow><b:mn>3</b:mn></b:msup></b:math>-bonded carbon. Here, we computed the binding energy values of C(1s) core electrons on the absolute energy scale for model structures of amorphous carbon (a-C) using density functional theory (DFT). The DFT calculations show that in the case of hydrogen-free a-C, the C(1s) binding energy for <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msup><c:mrow><c:mi>sp</c:mi></c:mrow><c:mn>3</c:mn></c:msup></c:math> carbon atoms is a distribution found approximately 1 eV higher than the binding energy distribution of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msup><d:mrow><d:mi>sp</d:mi></d:mrow><d:mn>2</d:mn></d:msup></d:math>-hybridized carbons. However, the introduction of hydrogen in the a-C network reduces the distance between the characteristic signals of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:msup><e:mrow><e:mi>sp</e:mi></e:mrow><e:mn>3</e:mn></e:msup></e:math>- and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msup><f:mrow><f:mi>sp</f:mi></f:mrow><f:mn>2</f:mn></f:msup></f:math>-bonded carbon due to the increased ability to screen the core hole by neighboring hydrogen atoms as compared to carbon atoms. This effect hinders the unambiguous quantification of the carbon hybridization state on the basis of C(1s) XPS data alone. This work can assist surface scientists in the use of XPS for the accurate characterization of carbon-based materials.

  PublisherOA PDFDOI

• Data from: First-principles investigation of surface mechanochemistry of transition metal phosphides under oxygen and benzene atmospheres

  Open MIND · 2025-12-11

  dataset

  Transition metal phosphides (TMPs) have aroused widespread research interest in the past decade due to their excellent electrical and mechanical properties. Nonetheless, their application in micro- and nanoelectromechanical systems (MEMS and NEMS) has not been investigated. Here, we use density functional theory (DFT) to explore the potential of four transition-metal phosphides to act as contact materials of MEMS/NEMS switches. Specifically, we first investigate the thermodynamic stability of Ru2P, RuP, Rh2P, and TiP under an oxygen environment. Then, using benzene as the background gas, the mechanical contact cycle is modeled to examine the process of tribopolymer formation on the surface of the contacts, which has been reported as the major reason for conductance loss after repeated actuation. The results show that Ru2P and Rh2P are excellent choices for avoiding friction-induced polymerization, making them promising contact materials for MEMS/NEMS switches.

  DOI

• Mechanochemistry at Nanoscale Metallic Contacts: How Stress and Voltage Drive Tribopolymerization

  ACS Applied Materials & Interfaces · 2025-09-02 · 2 citations

  articleSenior authorCorresponding

  Contact-induced reactions of interfacially confined molecules represent a widespread yet poorly understood class of mechanochemical phenomena, with broad implications for surface chemistry, tribology, and nanotechnology. Tribopolymerization─stress-induced polymerization of organic adsorbates into insulating nanolayers─causes conductance loss and limits the reliability of electrical contacts across length scales, particularly in nanoelectromechanical systems (NEMS). Using atomic force microscopy (AFM), we investigate how stress and voltage drive tribopolymer growth from ambient-adsorbed molecules in Pt/Pt nanocontacts. The measured kinetics follow a stress-assisted thermal activation model, confirming its mechanochemical origin. We develop a new contact-mechanics-corrected model that combines stress-dependent reaction kinetics with realistic contact mechanics. Using power-law tip geometries, this model accounts for inevitable wear-induced nonstandard tip shapes by integrating local reaction rates over the full, nonuniform stress distribution within the contact region. This enables accurate extraction of a unified activation volume (ΔV = 5.6 ± 1.4 Å3) across two decades of both contact area and stress, in sharp contrast to conventional analyses that neglect contact geometry and yield widely scattered activation volumes spanning 2 orders of magnitude. We further show that applied voltage accelerates tribopolymerization in a manner similar to stress, described through a newly introduced activation parameter and a field-induced bond-stretching model. Together, these results provide a general approach for quantifying coupled stress- and field-driven mechanochemical reactions at nanoscale interfaces, and offer mechanistic insights into tribopolymerization-induced electrical degradation of nanocontacts critical to device reliability.

  PublisherDOI

• A classical potential-based framework for modeling mechanochemical reactivity <i>via</i> molecular distortion: demonstration for a Diels–Alder reaction

  RSC Mechanochemistry · 2025-10-20 · 2 citations

  articleOpen access

  Atomistic simulations enhanced to capture force-induced distortion of reactant species enable exploration of how macroscopic stress states affect mechanochemical reactivity.

  PublisherOA PDFDOI

• First-Principles Investigation of Surface Mechanochemistry of Transition Metal Phosphides under Oxygen and Benzene Atmospheres

  ACS Applied Materials & Interfaces · 2025-04-03 · 2 citations

  article

  Transition metal phosphides (TMPs) have aroused widespread research interest in the past decade due to their excellent electrical and mechanical properties. Nonetheless, their application in micro- and nanoelectromechanical systems (MEMS and NEMS) has not been investigated. Here, we use density functional theory (DFT) to explore the potential of four transition-metal phosphides to act as contact materials of MEMS/NEMS switches. Specifically, we first investigate the thermodynamic stability of Ru2P, RuP, Rh2P, and TiP under an oxygen environment. Then, using benzene as the background gas, the mechanical contact cycle is modeled to examine the process of tribopolymer formation on the surface of the contacts, which has been reported as the major reason for conductance loss after repeated actuation. The results show that Ru2P and Rh2P are excellent choices for avoiding friction-induced polymerization, making them promising contact materials for MEMS/NEMS switches.

  PublisherDOI

Recent grants

• Collaborative Research: Multi-Scale Experiments and Modeling of Nanocrystalline Diamond Coatings for Dry Machining

  NSF · $150k · 2007–2010

• Collaborative Research: Dissipation in Atomic-Scale Friction - A Coordinated Experimental and Modeling Study

  NSF · $214k · 2008–2011

• Collaborative Research: Determining the Physical Mechanisms of Atomic Stick-Slip Friction by Closing the Gap between Experiments and Atomistic Simulations

  NSF · $287k · 2011–2014

• Collaborative Research: Nanoscale Interdisciplinary Team Research on Understanding and Overcoming Atomic-Level Wear in Tip-Based Nanomanufacturing

  NSF · $230k · 2008–2011

• GOALI: Enabling Ultra-Low Viscosity Lubricants Through Fundamental Understanding of Additive Interactions and Tribofilm Growth Mechanisms: An In-Situ Study

  NSF · $384k · 2017–2021

Frequent coauthors

• Frank Streller

  Intel (United States)

  186 shared

• Graham E. Wabiszewski

  Intel (United States)

  184 shared

• Andrew M. Rappe

  University of Pennsylvania

  175 shared

• David J. Srolovitz

  Chinese University of Hong Kong

  173 shared

• Yubo Qi

  171 shared

• Daniel B. Durham

  Argonne National Laboratory

  169 shared

• W Mueller -Von Fischer

  Eaton (United States)

  168 shared

• Fan Yang

  Xuzhou University of Technology

  168 shared

Labs

• Carpick Research GroupPI

Education

• Ph.D., Materials Science and Engineering

  University of California, Berkeley

  1999

• M.S., Materials Science and Engineering

  University of California, Berkeley

  1995

• B.S., Materials Science and Engineering

  University of California, Berkeley

  1993