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Advanced Colloids Experiment-1 (ACE-1)


Overview | Description | Applications | Operations | Results | Publications | Imagery

Experiment Overview

This content was provided by Matthew Lynch, Ph.D., Paul M. Chaikin, Ph.D., David A. Weitz, Ph.D., Arjun Yodh, Ph.D., Chang-Soo Lee, and is maintained in a database by the ISS Program Science Office.

Brief Summary

Advanced Colloids Experiment-1 (ACE-1) is the first in a series of microscopic imaging investigations of materials which contain small colloidal particles, which have the specific characteristic of remaining evenly dispersed and distributed within the material. This investigation takes advantage of the unique environment onboard the International Space Station (ISS) in order to separate the effects induced by Earth’s gravity in order to examine flow characteristics and the evolution and ordering effects within these colloidal materials. Engineering, manipulation and the fundamental understanding of materials of this nature potentially enhances our ability to produce, store, and manipulate materials which rely on similar physical properties.

Principal Investigator(s)

  • Matthew Lynch, Ph.D., Procter and Gamble, Cincinnati, OH, United States
  • Paul M. Chaikin, Ph.D., New York University, New York, NY, United States
  • David A. Weitz, Ph.D., Harvard University, Cambridge, MA, United States
  • Arjun Yodh, Ph.D., University of Pennsylvania, University Park, PA, United States
  • Chang-Soo Lee, Universiteit van Amsterdam, Netherlands
  • Co-Investigator(s)/Collaborator(s)

  • So-Young Han, Chungnam National University, Daejeon, South Korea
  • Thomas Kodger, Harvard University, Cambridge, MA, United States
  • Peter J. Lu, Ph.D., Harvard University, Cambridge, MA, United States
  • Stefano Sacanna, Ph.D., New York University, New York, NY, United States
  • Nadrian Seeman, New York University, New York, NY, United States
  • Tim Still, University of Pennsylvania, University Park, PA, United States
  • Peter Yunker, Ph.D., University of Pennsylvania, University Park, PA, United States
  • Marco Potenza, Ph.D., University of Amsterdam, Amsterdam, Netherlands
  • Andrew Hollingsworth, Ph.D., New York University, New York, NY, United States
  • Chang-Hyung Choi, Chungnam National University, Daejeon, South Korea
  • Stefano Buzzaccaro, ESA
  • Roberto Piazza, European Space Agency (ESA)
  • Ke Chen, University of Pennsylvania, PA, United States
  • Luca Cipelletti, Ph.D., Universite Monpellier II, Monpellier, France
  • Matthew Gratale, Ph.D., Department of Physics & Astronomy, University Park, PA, United States
  • Developer(s)

    ZIN Technologies Incorporated, Cleveland, OH, United States

    Sponsoring Space Agency

    National Aeronautics and Space Administration (NASA)

    Sponsoring Organization

    Human Exploration and Operations Mission Directorate (HEOMD)

    Research Benefits

    Information Pending

    ISS Expedition Duration:

    May 2012 - March 2014

    Expeditions Assigned


    Previous ISS Missions

    The Preliminary Advanced Colloids Experiment (PACE) is an engineering evaluation of the capabilities and limitations of the ACE hardware. With PACE special attention is paid to vibration effects on image resolution when using ACE hardware during times of astronaut activity and sleep.

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    Experiment Description

    Research Overview

    • The Advanced Colloids Experiment-1 (ACE-1) investigation intends to address fundamental and applied questions in the field of soft condensed matter physics.

    • A goal of this research is to probe and understand particle scale relationships and extend the application of this knowledge from fundamental physics to technological applications.

    • Soft condensed matter materials are easily deformable by external stresses, electric or magnetic fields, or even by thermal fluctuations. These materials typically possess structures which are much larger than atomic or molecular scales; the structure and dynamics at intermediate scales (i.e., mesoscopic scales) determine large scale (i.e., macroscopic) physical properties.

    • The availability of a space-based microscope, with the ability to support the future addition of a confocal head, enables microscopic imaging (and later 3D microscopic imaging) that allows scientists to remove the need to theoretically model macroscopic images in order to couple observations with the underlying physics.

    • The Advanced Colloids Experiment (ACE-1) is the first step along the path to understanding in detail (at the particle level) how it is that order arises out of disorder and how nature organizes when not affected by gravity.


    The Advanced Colloids Experiment-1 (ACE-1) incorporates hundreds of individual samples, and these samples all differ in type or concentration. There is a broad array of fundamental questions being studied by the ACE-1 scientists; for example, how does one understand the basic physics that describes the time-dependent evolution in the microstructure in concentrated dispersions? This is a complex problem because of the interplay of inter-particle, Brownian (i.e., random particle collision) and hydrodynamic (i.e., particle drag) forces and thermodynamics. Procter and Gamble (P&G), for example, hopes to measure the rate of coarsening (i.e., the process of whereby particles shrink or grow as a result of diffusion of a solute) of weak depletion gels (i.e., weak stress bearing gels) to compare to delayed sedimentation in earth-based samples. These microgravity experiments allow a significant simplification of the problem (e.g. by eliminating sedimentation from gravitational stress).

    This work also provides some very unique opportunities to study the shelf-life problem. Fundamental microgravity research at Harvard University by Weitz and Lu and at (P&G) by Lynch and Kodger on the underlying fluid physics may provide the understanding needed to enable the development of better, less expensive, longer shelf-life household products, foods, and medicines. Stabilizers, which are presently used in these products, are expensive, take up volume, and are needed to extend the life of products. Even a 1% savings for a $100 billion dollar industry would prove significant. To present, the P&G microgravity experimental designs have been relatively simple, whereby samples are stirred and changes are measured at low magnification with a camera. To connect the physics to the observations, it becomes necessary to evoke phase separation theories. The advent of a space-based confocal microscope, in the future, allows one to remove the need to macroscopically model images of the underlying physics. Scientists at P&G feel that measuring the movement of individual particles directly enhances their ability to move the science forward. Specific objectives being addressed by this research and by different investigators are as follows:

    • The technology now exists to create lock-and-key reactions (i.e., reactions that only work given specific end member reagents) with the possibility of creating self-replicating non-biological structures from nanoscale building blocks using colloidal self-assembly. Additionally, the crystallization of ellipsoids, cubes, and other shapes should be enabled by the new materials used for containing ACE-1 samples (Chaikin, Hollingsworth, Pine, Sacanna, and Seeman - New York University).

    • Visually monitoring and controlling how colloidal structures form and evolve when gravitational masking is removed enables colloidal engineering (Weitz and Lu ? Harvard University; Lynch and Kodger - Procter and Gamble).

    • With polymers and microgels that change size with temperature, the processes of melting and crystallization is observed at the level of the individual particles using model "atomic" systems (Yodh, Chen, Gratale, Still, and Yunker - University of Pennsylvania).

    • Study the birth, structure and evolution of depletion gels in microgravity. Short-range attractive interactions between colloidal particles provide a unique way to trigger the formation of colloidal gels with tunable strength. (Buzzaccaro, Piazza ? Milan/ESA and Cipelletti - Montpellier/ESA).

    • Study colloidal superstructures in space where anisotropic interactions are temperature controlled using critical Casimir forces (Schall, Veen, Wegdam - University of Amsterdam and Potenza - Milan/ESA).

    • Study microscopic self-assembly in microgravity using fabricated anisotropic Janus particles (i.e., particles that have opposite attractive properties on opposite surfaces) (Lee, Choi, Han and Jung - Chungnam National University).

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    Space Applications

    ACE-1addresses basic physics questions with regards to colloids, but some of the results may eventually have applications for space exploration. Supercritical fluids, which represent one of the applications of the critical point (i.e., phase boundary) experiment, are a potential application in propulsion systems for future spacecraft design. Additionally, associated shelf-life studies impact not only products on store shelves, but those being stored for later use in space.

    Earth Applications

    The ACE-1 samples provide important data that is not available on Earth; data which can guide our understanding of crystallization, production quality control and phase separation (e.g., shelf-life and product collapse). Additionally, since product shelf-life may be dependent upon binodal decomposition and possibly upon Oswald ripening in the emulsion samples, a better understanding of these processes could have an enormous commercial impact in terms of quality, production, and longevity.

    These colloidal materials have applications ranging from the very mundane to the very esoteric. Particle additives, for example, offer practical control of fluid rheologies, improving the performances of conventional materials such as paints, motor oils, food, and cosmetics, while further offering insights into microfluidics and cell biology processes. Control of particles on micro and nano-scales also hold potential regarding high-tech problems such as photonics, lithography, biochemical sensors and processors, as well as in the design of advanced composites. In a different vein, studies of complex fluids are increasingly stimulated by analogies from cell biology, and in some cases provide critical insights about mechanisms that arise in the crowded, aqueous, and near-room-temperature cellular environments. The development of micro- and nano-particle fluid suspensions and colloids plays a major role in many industries. One example is drug-delivery within the biomedical market, where these systems and their development result in billions of dollars in sales for the pharmaceutical industry.

    Generally, colloidal nucleation experiments seek an understanding of the most fundamental liquid/solid transitions. Particle shape impacts the rise of order out of disorder. Particles can be fabricated which enable self-assembly and the self-replication of structures. Though direct applications of that understanding do not yet drive the research, the growth of ordered colloidal phases has attracted interest in a number of areas, e.g., ceramics, composites, optical filters and photonic band-gap materials. For example, the use of asymmetric particles may produce directionally dependent crystal properties, and the use of particles whose size depends upon temperature may afford temperature tunable crystals.

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    Operational Requirements

    The ACE-1 investigation consists of twenty sample disks that each contains up to ten wells of colloidal particles (each sample well typically contain 2.1 microliters). One set of ten disks launches around June of 2012 and an additional set of ten disks launch 12 to 16 months later, and perhaps incrementally. The experiment requires crewmember time to set-up in the Light Microscopy Module (LMM) facility on the ISS. The samples in each sample disk are mixed and then observed, one disk at a time. The microscope is controlled from the ground and the pictures are down-linked to investigators for analysis and planning.

    Operational Protocols

    ACE-1 Operations: Crewmember required to install ACE-1 hardware, Power to rack is OFF

    • Visually inspect ACE-1 sample cell for broken materials.

    • Initially, use horizontal magnet mounted in drill chuck to stir particles if installing particle sample cell. With development, electrically driven magnets built into the sample holders are used to homogenize the less viscous samples.

    • Remove sample cell from ziplock bag.

    • Install sample cell onto ACE-1 sample holder.

    • Install LMM AFC Front Door.
    ACE-1 Operations: Crewmember required, Powered operations, Oil used.
    • Crewmember moves LMM to operations position (rotated into rack).

    • Crewmember closes FIR rack doors and moves power switches into ON position.

    • Rack is commanded ON from ground.
    ACE-1 Operations: Ground controlled operations
    • The motorized X-Y Stage is commanded to align the sample wells with the objective.

    • The microscope Z-Axis is commanded to immerse the objective into the immersion oil and focus on the target.

    • Objective is moved through the oil by translation of the X-Y Stage.

    • Data acquired and stored for later downlink.
    ACE-1 Operations: Crewmember required, remove/replace oil dispenser, Power to rack is OFF
    • 1. (Using AFC gloves)

    • Use a microfiber wipe to clean oil from test target and microscope objective.

    • Place used wipe into zip lock bag with used dispenser. Temporarily stow inside AFC.

    • Remove AFC transfer doors (bottom of AFC).
    2. (No AFC gloves)
    • Place bag with new dispenser into AFC. Temporarily stow inside AFC.

    • Remove bag containing used wipe and used dispenser. Mark for disposal.
    3. (Using AFC gloves)
    • Replace AFC transfer doors.

    • Proceed to oil dispensing procedures.

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    Results/More Information

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    Related Websites
  • ISS Research Project-ACE-1
  • Materials Research Science & Engineering Center (MRSEC) at the University of Pennsylvania
  • The Laboratory for Research on the Structure of Matter at the University of Pennsylvania
  • Chaikinlab, New York University
  • Professor David Weitz, Harvard University
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    ACE-1 Sample disk holder (back light included). 

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    image ACE-1 Sample Disk Modules.
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    image Light Microscopy Module (LMM) facility; a component part of the Fluids Integrated Rack (FIR).
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    image Graphic of ACE-1 installed in the Light Microscopy Module (LMM) facility.
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    image Crewmember T.J. Creamer working at the Microscopy Module (LMM) facility.
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    Information provided by the investigation team to the ISS Program Scientist's Office.
    If updates are needed to the summary please contact JSC-ISS-Program-Science-Group. For other general questions regarding space station research and technology, please feel free to call our help line at 281-244-6187 or e-mail at JSC-ISS-Research-Helpline.