Christopher D. F. Honig | University of Melbourne (original) (raw)

Papers by Christopher D. F. Honig

9th Research in Engineering Education Symposium (REES 2021) and 32nd Australasian Association for Engineering Education Conference (REES AAEE 2021), 2022

The ongoing coronavirus pandemic required us to quickly adapt and familiarise ourselves with new ... more The ongoing coronavirus pandemic required us to quickly adapt and familiarise ourselves with new skills and technologies in the shift to online teaching. Irregular communication due to extended lockdowns has meant that while knowledge on effective online teaching has been developed, this knowledge has not been properly disseminated to our junior teaching staff. As they operate predominantly in student-facing positions, it is essential that our junior staff be equipped with information on best practice in online teaching as well as with an awareness of the resources available to support them. PURPOSE OR GOAL To address the gap outlined above, we developed a new professional development program for our junior teaching staff, focusing mainly on online teaching. The goal was to share our collective knowledge on best practice in online teaching, and to demonstrate how various technologies could aid in promoting active learning in an online setting. The program also aimed to initiate a community of practice around teaching and the online teaching space. APPROACH OR METHODOLOGY/METHODS In designing our program, we considered student feedback from previous semesters, and more recent feedback on the online teaching experience from 2020. The final program covered the following topics: general advice, navigating Zoom and physical setup for online teaching, online tools for active learning, engagement within teaching teams, online feedback, and blended synchronous learning. Tools and technologies showcased in the program were embedded in the delivery to allow first-hand experience. ACTUAL OR ANTICIPATED OUTCOMES An exit survey indicated that in general, participants found the program useful, with an average rating of 8.27 (out of 10). The top areas that participants indicated that they would like more assistance were quizzes and tools for active learning (31%), providing feedback to students (22%), and blended synchronous learning (20%). Zoom (12%) and the physical setup for online teaching (15%) did not rank highly, in line with our observation that a large percentage of participants had some prior experience with online teaching in 2020. CONCLUSIONS/RECOMMENDATIONS/SUMMARY In summary, we piloted a professional development focused mainly on online-teaching for junior staff. The program was well-received, and the collected feedback will used for implementation and improvement of future run.

First Monday, Feb 11, 2017

By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create... more By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create geographical and temporal maps of street art in Melbourne, mediated through the collective eye of Instagram. Apart from merely identifying the most popular images, geo-tagged metadata allows us to create spatial heat maps to identify physical locations of high-image production. Caption data beneath the images allows us to search for high frequency words, which we use to identify patterns within the online audience’s relationship to street art. Finally by simply plotting out the number of images produced each day and cross-referencing with the corresponding caption data, we are able to identify historically significant events within Melbourne’s street art culture. The analysis is easy to use, even for a researcher with minimal programming experience and can be used to project cultural trends (beneath any hashtag) or as a tool to navigate historical Big Data within a conservation context.

Elmi əsərlər, Jun 30, 2011

Education for Chemical Engineers, Apr 1, 2022

This paper discusses alternatives to on-campus teaching laboratories, to allow for hands-on learn... more This paper discusses alternatives to on-campus teaching laboratories, to allow for hands-on learning for remote students. Wholly online practical equivalents have become increasingly popular post-COVID (online simulations or processing experimental data only) which can offer lower overheads and easy scale-up, but often miss hands-on learning outcomes. This paper reviews opportunities for mail-out practicals, where the equipment is delivered to students’ homes, combined with live synchronous learning activities via video streaming or online software. The combination of mail-out experimental kits plus synchronous interactive learning activities creates a host of new opportunities for teaching to remote students. Complimentary online teaching activities could include direct interaction with teaching staff or other students, but it can also be real-time simulations of their experiment. The paper presents a specific case study for a 2nd year undergraduate chemical engineering heat exchanger practical, that facilitated hands-on practical learning with synchronous online activities during COVID-19 campus closure. The paper uses a mixed methods approach in a 2 year study to assess student learning outcomes.

First Monday, 2017

By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create... more By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create geographical and temporal maps of street art in Melbourne, mediated through the collective eye of Instagram. Apart from merely identifying the most popular images, geo-tagged metadata allows us to create spatial heat maps to identify physical locations of high-image production. Caption data beneath the images allows us to search for high frequency words, which we use to identify patterns within the online audience’s relationship to street art. Finally by simply plotting out the number of images produced each day and cross-referencing with the corresponding caption data, we are able to identify historically significant events within Melbourne’s street art culture. The analysis is easy to use, even for a researcher with minimal programming experience and can be used to project cultural trends (beneath any hashtag) or as a tool to navigate historical Big Data within a conservation context.

First Monday, 2016

This paper provides an accessible methodology for mapping audience-constructed genres using the o... more This paper provides an accessible methodology for mapping audience-constructed genres using the online image-sharing platform Instagram. We apply the method to classify artists who utilize public space in relation to the categories ‘street art’ and ‘graffiti bombing’ based on correlations between an artist’s Instagram follower audience and general ‘street art’ and ‘graffiti bombing’ accounts. By measuring the artist’s audience at different times, we can map not only their specific audience composition but also project their demographic trajectory. Finally we provide a methodology to estimate the total online audience for a specific genre: how many total Instagram accounts might follow street art content? This methodology can function as a powerful analytical tool, but is also easy to use, even for a researcher with limited mathematical or programming experience.

This thesis describes the study of the hydrodynamic boundary condition at the solid−liquid interf... more This thesis describes the study of the hydrodynamic boundary condition at the solid−liquid interface using the colloidal probe Atomic Force Microscope. Quantitative comparison between measured lubrication forces and theoretical lubrication forces show that the measured forces agree with theory when the no slip boundary condition is employed. We measure an effective slip length of 0 ± 2 nm at shear rates up to 250,000 sec-1. Our results are consistent with the Taylor lubrication equation without the need to invoke a slip length fitting parameter. Our results are also consistent with molecular dynamic simulations that predict no slip at the shear rates that are currently experimentally accessible.

9th Research in Engineering Education Symposium (REES 2021) and 32nd Australasian Association for Engineering Education Conference (REES AAEE 2021), 2022

We describe a new method, correlation force spectrometry, which characterizes fluids through meas... more We describe a new method, correlation force spectrometry, which characterizes fluids through measurement of the correlations between the thermally-stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss applications to measurement of the rheological properties of complex fluids at high frequency and high spatial resolution. We measure a large range of frequencies (up to 1 MHz) and use very small sample volumes (μL) and demonstrate that the thermal noise in the cross correlation is much smaller than in the autocorrelation. Our experimental measurements of the equilibrium fluctuations in cantilever displacement for cantilever pairs immersed in a Newtonian fluid are described accurately using a theoretical approach based upon the fluctuation-dissipation theorem [Paul and Cross, Phys. Rev. Lett. 92, 235501 (2004)].

Review of Scientific Instruments, 2012

We describe a method, correlation force spectrometry (CFS), which characterizes fluids through me... more We describe a method, correlation force spectrometry (CFS), which characterizes fluids through measurement of the correlations between the thermally stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss a major application: measurement of the rheological properties of fluids at high frequency and high spatial resolution. Use of CFS as a rheometer is validated by comparison between experimental data and finite element modeling of the deterministic ringdown of cantilevers using the known viscosity of fluids. The data can also be accurately fitted using a harmonic oscillator model, which can be used for rapid rheometric measurements after calibration. The method is non-invasive, uses a very small amount of fluid, and has no actively moving parts. It can also be used to analyze the rheology of complex fluids. We use CFS to show that (non-Newtonian) aqueous polyethylene oxide solution can be modeled approximately by incorporating an elastic spring between the cantilevers.

Journal of Physical Chemistry C, 2007

ABSTRACT

The Journal of Physical Chemistry C, 2008

... Christopher DF Honig † and William A. Ducker* † ‡. Department of Chemical and Biomolecular En... more ... Christopher DF Honig † and William A. Ducker* † ‡. Department of Chemical and Biomolecular Engineering, and Particulate Fluids Processing Centre, University of Melbourne, Melbourne 3010, Australia, and Department of ...

The Journal of Physical Chemistry C, 2011

Lubrication forces between hydrophobized glass surfaces in alkane liquids have been measured usin... more Lubrication forces between hydrophobized glass surfaces in alkane liquids have been measured using the atomic force microscopy colloid probe technique and compared to Reynolds lubrication theory with the aim of understanding the nature of the solid− liquid ...

The Journal of Physical Chemistry C, 2010

We show that a thin organic film has a significant effect on the lubrication force (damping) acti... more We show that a thin organic film has a significant effect on the lubrication force (damping) acting on a smooth sphere approaching a smooth flat plate in a gaseous environment. The lubrication forces were determined by the analysis of the width of a power spectrum density of the vibrations of an atomic force microscope cantilever that is attached to the sphere and immersed in the gas at thermal equilibrium. Because the lubrication force is determined by the collisions of gas molecules with both the sphere and the plate, the lubrication force was used to determine the thermal accommodation coefficient of the gas on the solids. We find that clean glass surfaces in ambient air at ∼25°C exhibit a slip length of 630 ( 90 nm per surface and a concomitant accommodation coefficient of 0.19, whereas a glass plate with a ∼1 nm organic film of trimethylsilane exhibits a slip length of 270 ( 90 nm and an accommodation coefficient of 0.43. If left in air for an extended period of time, the slip length on clean glass surfaces falls, which is consistent with the spontaneous adsorption of airborne contaminants. Thus, our analysis can be used as a simple, nondestructive method for detecting the presence of contaminants or other films on solids.

Review of Scientific Instruments, 2005

ABSTRACT

Physical Review Letters, 2007

We describe measurement and interpretation of the force acting on a smooth hydrophilic glass part... more We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid (1-100 microm s(-1) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions (0.001 Pa s<eta<0.090 Pa s). We find that the force is accurately described by Reynolds lubrication theory with a no-slip boundary condition, even at maximum strain rates of up to 250 000 s(-1). Compared to earlier studies of hydrodynamic forces on small particles, we reduce the uncertainty in the absolute particle-plate separation by using an evanescent-wave measurement of the separation.

Physical Review E, 2010

By analysis of the thermally driven oscillation of an atomic force microscope ͑AFM͒ cantilever, w... more By analysis of the thermally driven oscillation of an atomic force microscope ͑AFM͒ cantilever, we have measured both the damping and static forces acting on a sphere near a flat plate immersed in gas. By varying the proximity of the sphere to the plate, we can continuously vary the Knudsen number ͑Kn͒ at constant pressure, thereby accessing the slip flow, transition, and molecular regimes at a single pressure. We use measurements in the slip-flow regime to determine the combined slip length ͑on both sphere and plate͒ and the tangential momentum accommodation coefficient, . For ambient air at 1 atm between two methylated glass solids, the inverse damping is linear with separation and the combined slip length on both surfaces is 250 nmϮ 100 nm, which corresponds to = 0.77Ϯ 0.24. At small separations ͑KnϾ 0.4͒ the measured inverse damping is no longer linear with separation, and is observed to exhibit reasonable agreement with the Vinogradova formula.

Journal of Applied Physics, 2013

The dynamical-mechanical properties of a small region of fluid can be measured using two closely ... more The dynamical-mechanical properties of a small region of fluid can be measured using two closely spaced thermally stimulated micrometer-scale cantilevers. We call this technique correlation force spectroscopy (CFS). We describe an instrument that is designed for characterizing the extensional properties of polymer molecules that straddle the gap between the two cantilevers and use it to measure the stiffness and damping (molecular friction) of a dextran molecule. The device is based on a commercial atomic force microscope, into which we have incorporated a second antiparallel cantilever. The deflection of each cantilever is measured in the frequency range dc-1 MHz and is used to generate the cross-correlation at equilibrium. The main advantage of cross-correlation measurements is the reduction in thermal noise, which sets a fundamental noise limit to force resolution. We show that the thermal noise in our cross-correlation measurements is less than one third of the value for single-cantilever force microscopy. The dynamics of the cantilever pair is modeled using the deterministic motion of a harmonic oscillator initially displaced from equilibrium, which yields the equilibrium auto and cross-correlations in cantilever displacement via the fluctuation-dissipation theorem. Fitted parameters from the model (stiffness and damping) are used to characterize the fluid at equilibrium, including any straddling molecules. V C 2013 American Institute of Physics. [http://dx.

9th Research in Engineering Education Symposium (REES 2021) and 32nd Australasian Association for Engineering Education Conference (REES AAEE 2021), 2022

The ongoing coronavirus pandemic required us to quickly adapt and familiarise ourselves with new ... more The ongoing coronavirus pandemic required us to quickly adapt and familiarise ourselves with new skills and technologies in the shift to online teaching. Irregular communication due to extended lockdowns has meant that while knowledge on effective online teaching has been developed, this knowledge has not been properly disseminated to our junior teaching staff. As they operate predominantly in student-facing positions, it is essential that our junior staff be equipped with information on best practice in online teaching as well as with an awareness of the resources available to support them. PURPOSE OR GOAL To address the gap outlined above, we developed a new professional development program for our junior teaching staff, focusing mainly on online teaching. The goal was to share our collective knowledge on best practice in online teaching, and to demonstrate how various technologies could aid in promoting active learning in an online setting. The program also aimed to initiate a community of practice around teaching and the online teaching space. APPROACH OR METHODOLOGY/METHODS In designing our program, we considered student feedback from previous semesters, and more recent feedback on the online teaching experience from 2020. The final program covered the following topics: general advice, navigating Zoom and physical setup for online teaching, online tools for active learning, engagement within teaching teams, online feedback, and blended synchronous learning. Tools and technologies showcased in the program were embedded in the delivery to allow first-hand experience. ACTUAL OR ANTICIPATED OUTCOMES An exit survey indicated that in general, participants found the program useful, with an average rating of 8.27 (out of 10). The top areas that participants indicated that they would like more assistance were quizzes and tools for active learning (31%), providing feedback to students (22%), and blended synchronous learning (20%). Zoom (12%) and the physical setup for online teaching (15%) did not rank highly, in line with our observation that a large percentage of participants had some prior experience with online teaching in 2020. CONCLUSIONS/RECOMMENDATIONS/SUMMARY In summary, we piloted a professional development focused mainly on online-teaching for junior staff. The program was well-received, and the collected feedback will used for implementation and improvement of future run.

First Monday, Feb 11, 2017

By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create... more By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create geographical and temporal maps of street art in Melbourne, mediated through the collective eye of Instagram. Apart from merely identifying the most popular images, geo-tagged metadata allows us to create spatial heat maps to identify physical locations of high-image production. Caption data beneath the images allows us to search for high frequency words, which we use to identify patterns within the online audience’s relationship to street art. Finally by simply plotting out the number of images produced each day and cross-referencing with the corresponding caption data, we are able to identify historically significant events within Melbourne’s street art culture. The analysis is easy to use, even for a researcher with minimal programming experience and can be used to project cultural trends (beneath any hashtag) or as a tool to navigate historical Big Data within a conservation context.

Elmi əsərlər, Jun 30, 2011

Education for Chemical Engineers, Apr 1, 2022

This paper discusses alternatives to on-campus teaching laboratories, to allow for hands-on learn... more This paper discusses alternatives to on-campus teaching laboratories, to allow for hands-on learning for remote students. Wholly online practical equivalents have become increasingly popular post-COVID (online simulations or processing experimental data only) which can offer lower overheads and easy scale-up, but often miss hands-on learning outcomes. This paper reviews opportunities for mail-out practicals, where the equipment is delivered to students’ homes, combined with live synchronous learning activities via video streaming or online software. The combination of mail-out experimental kits plus synchronous interactive learning activities creates a host of new opportunities for teaching to remote students. Complimentary online teaching activities could include direct interaction with teaching staff or other students, but it can also be real-time simulations of their experiment. The paper presents a specific case study for a 2nd year undergraduate chemical engineering heat exchanger practical, that facilitated hands-on practical learning with synchronous online activities during COVID-19 campus closure. The paper uses a mixed methods approach in a 2 year study to assess student learning outcomes.

First Monday, 2017

By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create... more By scraping metadata from Instagram images tagged with #MelbourneStreetArt, we are able to create geographical and temporal maps of street art in Melbourne, mediated through the collective eye of Instagram. Apart from merely identifying the most popular images, geo-tagged metadata allows us to create spatial heat maps to identify physical locations of high-image production. Caption data beneath the images allows us to search for high frequency words, which we use to identify patterns within the online audience’s relationship to street art. Finally by simply plotting out the number of images produced each day and cross-referencing with the corresponding caption data, we are able to identify historically significant events within Melbourne’s street art culture. The analysis is easy to use, even for a researcher with minimal programming experience and can be used to project cultural trends (beneath any hashtag) or as a tool to navigate historical Big Data within a conservation context.

First Monday, 2016

This paper provides an accessible methodology for mapping audience-constructed genres using the o... more This paper provides an accessible methodology for mapping audience-constructed genres using the online image-sharing platform Instagram. We apply the method to classify artists who utilize public space in relation to the categories ‘street art’ and ‘graffiti bombing’ based on correlations between an artist’s Instagram follower audience and general ‘street art’ and ‘graffiti bombing’ accounts. By measuring the artist’s audience at different times, we can map not only their specific audience composition but also project their demographic trajectory. Finally we provide a methodology to estimate the total online audience for a specific genre: how many total Instagram accounts might follow street art content? This methodology can function as a powerful analytical tool, but is also easy to use, even for a researcher with limited mathematical or programming experience.

This thesis describes the study of the hydrodynamic boundary condition at the solid−liquid interf... more This thesis describes the study of the hydrodynamic boundary condition at the solid−liquid interface using the colloidal probe Atomic Force Microscope. Quantitative comparison between measured lubrication forces and theoretical lubrication forces show that the measured forces agree with theory when the no slip boundary condition is employed. We measure an effective slip length of 0 ± 2 nm at shear rates up to 250,000 sec-1. Our results are consistent with the Taylor lubrication equation without the need to invoke a slip length fitting parameter. Our results are also consistent with molecular dynamic simulations that predict no slip at the shear rates that are currently experimentally accessible.

9th Research in Engineering Education Symposium (REES 2021) and 32nd Australasian Association for Engineering Education Conference (REES AAEE 2021), 2022

We describe a new method, correlation force spectrometry, which characterizes fluids through meas... more We describe a new method, correlation force spectrometry, which characterizes fluids through measurement of the correlations between the thermally-stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss applications to measurement of the rheological properties of complex fluids at high frequency and high spatial resolution. We measure a large range of frequencies (up to 1 MHz) and use very small sample volumes (μL) and demonstrate that the thermal noise in the cross correlation is much smaller than in the autocorrelation. Our experimental measurements of the equilibrium fluctuations in cantilever displacement for cantilever pairs immersed in a Newtonian fluid are described accurately using a theoretical approach based upon the fluctuation-dissipation theorem [Paul and Cross, Phys. Rev. Lett. 92, 235501 (2004)].

Review of Scientific Instruments, 2012

We describe a method, correlation force spectrometry (CFS), which characterizes fluids through me... more We describe a method, correlation force spectrometry (CFS), which characterizes fluids through measurement of the correlations between the thermally stimulated vibrations of two closely spaced micrometer-scale cantilevers in fluid. We discuss a major application: measurement of the rheological properties of fluids at high frequency and high spatial resolution. Use of CFS as a rheometer is validated by comparison between experimental data and finite element modeling of the deterministic ringdown of cantilevers using the known viscosity of fluids. The data can also be accurately fitted using a harmonic oscillator model, which can be used for rapid rheometric measurements after calibration. The method is non-invasive, uses a very small amount of fluid, and has no actively moving parts. It can also be used to analyze the rheology of complex fluids. We use CFS to show that (non-Newtonian) aqueous polyethylene oxide solution can be modeled approximately by incorporating an elastic spring between the cantilevers.

Journal of Physical Chemistry C, 2007

ABSTRACT

The Journal of Physical Chemistry C, 2008

... Christopher DF Honig † and William A. Ducker* † ‡. Department of Chemical and Biomolecular En... more ... Christopher DF Honig † and William A. Ducker* † ‡. Department of Chemical and Biomolecular Engineering, and Particulate Fluids Processing Centre, University of Melbourne, Melbourne 3010, Australia, and Department of ...

The Journal of Physical Chemistry C, 2011

Lubrication forces between hydrophobized glass surfaces in alkane liquids have been measured usin... more Lubrication forces between hydrophobized glass surfaces in alkane liquids have been measured using the atomic force microscopy colloid probe technique and compared to Reynolds lubrication theory with the aim of understanding the nature of the solid− liquid ...

The Journal of Physical Chemistry C, 2010

We show that a thin organic film has a significant effect on the lubrication force (damping) acti... more We show that a thin organic film has a significant effect on the lubrication force (damping) acting on a smooth sphere approaching a smooth flat plate in a gaseous environment. The lubrication forces were determined by the analysis of the width of a power spectrum density of the vibrations of an atomic force microscope cantilever that is attached to the sphere and immersed in the gas at thermal equilibrium. Because the lubrication force is determined by the collisions of gas molecules with both the sphere and the plate, the lubrication force was used to determine the thermal accommodation coefficient of the gas on the solids. We find that clean glass surfaces in ambient air at ∼25°C exhibit a slip length of 630 ( 90 nm per surface and a concomitant accommodation coefficient of 0.19, whereas a glass plate with a ∼1 nm organic film of trimethylsilane exhibits a slip length of 270 ( 90 nm and an accommodation coefficient of 0.43. If left in air for an extended period of time, the slip length on clean glass surfaces falls, which is consistent with the spontaneous adsorption of airborne contaminants. Thus, our analysis can be used as a simple, nondestructive method for detecting the presence of contaminants or other films on solids.

Review of Scientific Instruments, 2005

ABSTRACT

Physical Review Letters, 2007

We describe measurement and interpretation of the force acting on a smooth hydrophilic glass part... more We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid (1-100 microm s(-1) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions (0.001 Pa s<eta<0.090 Pa s). We find that the force is accurately described by Reynolds lubrication theory with a no-slip boundary condition, even at maximum strain rates of up to 250 000 s(-1). Compared to earlier studies of hydrodynamic forces on small particles, we reduce the uncertainty in the absolute particle-plate separation by using an evanescent-wave measurement of the separation.

Physical Review E, 2010

By analysis of the thermally driven oscillation of an atomic force microscope ͑AFM͒ cantilever, w... more By analysis of the thermally driven oscillation of an atomic force microscope ͑AFM͒ cantilever, we have measured both the damping and static forces acting on a sphere near a flat plate immersed in gas. By varying the proximity of the sphere to the plate, we can continuously vary the Knudsen number ͑Kn͒ at constant pressure, thereby accessing the slip flow, transition, and molecular regimes at a single pressure. We use measurements in the slip-flow regime to determine the combined slip length ͑on both sphere and plate͒ and the tangential momentum accommodation coefficient, . For ambient air at 1 atm between two methylated glass solids, the inverse damping is linear with separation and the combined slip length on both surfaces is 250 nmϮ 100 nm, which corresponds to = 0.77Ϯ 0.24. At small separations ͑KnϾ 0.4͒ the measured inverse damping is no longer linear with separation, and is observed to exhibit reasonable agreement with the Vinogradova formula.

Journal of Applied Physics, 2013

The dynamical-mechanical properties of a small region of fluid can be measured using two closely ... more The dynamical-mechanical properties of a small region of fluid can be measured using two closely spaced thermally stimulated micrometer-scale cantilevers. We call this technique correlation force spectroscopy (CFS). We describe an instrument that is designed for characterizing the extensional properties of polymer molecules that straddle the gap between the two cantilevers and use it to measure the stiffness and damping (molecular friction) of a dextran molecule. The device is based on a commercial atomic force microscope, into which we have incorporated a second antiparallel cantilever. The deflection of each cantilever is measured in the frequency range dc-1 MHz and is used to generate the cross-correlation at equilibrium. The main advantage of cross-correlation measurements is the reduction in thermal noise, which sets a fundamental noise limit to force resolution. We show that the thermal noise in our cross-correlation measurements is less than one third of the value for single-cantilever force microscopy. The dynamics of the cantilever pair is modeled using the deterministic motion of a harmonic oscillator initially displaced from equilibrium, which yields the equilibrium auto and cross-correlations in cantilever displacement via the fluctuation-dissipation theorem. Fitted parameters from the model (stiffness and damping) are used to characterize the fluid at equilibrium, including any straddling molecules. V C 2013 American Institute of Physics. [http://dx.