Microchannel Diffusion (Microchannel Diffusion) - 07.12.17

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

ISS Science for Everyone

Science Objectives for Everyone
Medicine, biology, computer science and many other fields benefit from nanotechnology, in which interactions happen at an atomic level, but some of the most basic physical processes are different at such small scales. Fluid dynamics in particular are different because flowing molecules might interact more with the surfaces of channels than with each other. Microchannel Diffusion takes advantage of microgravity to study these interactions at slightly larger scales, providing a new understanding of particle flows at the nanoscale.
Science Results for Everyone
Information Pending

The following content was provided by Stefanie Countryman, M.B.A., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Microchannel Diffusion

Principal Investigator(s)
Alessandro Grattoni, Ph.D., Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX, United States

Giancarlo Canavese, Ph.D., Politecnico di Torino, Torino, Italy

BioServe Space Technologies, University of Colorado, Boulder, CO, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
National Laboratory (NL)

Research Benefits
Space Exploration, Earth Benefits, Scientific Discovery

ISS Expedition Duration
March 2016 - September 2016

Expeditions Assigned

Previous Missions
Information Pending

^ back to top

Experiment Description

Research Overview

  • Despite the increasing focus on nanofluidics in many of these applications, the laws governing molecular transport through nanoscale fluidic channels have not been fully realized.
  • The objective of Microchannel Diffusion is to provide insight into how microparticles interact with the surface of confining microchannels in the absence of gravitational forces.
  • The analysis focuses on understanding how physical and electrostatic confinement affect the diffusive transport of microparticles in microchannels.
  • The insight into confined diffusive transport is relevant for “on- Earth” applications including drug delivery, molecular sieving and particle filtration.
  • The study provides an understanding of microparticle diffusive transport, which can be important for future technological applications for space exploration.

The emergent properties of materials and devices fabricated with critical dimensions in the nanoscale present significant opportunities in the fields of medicine and biology for engineering of pharmaceutical delivery vehicles, therapeutic and imaging agents, and biological sensors. Despite the increasing focus on nanofluidics in many of these applications, the laws governing molecular transport through nanoscale fluidic channels have not been fully realized. As the size of the channel is reduced to the molecule size, classical continuum theories fail to predict even basic characteristics of fluid transport. New transport mechanisms are observed whereby channel surface properties begin to dominate over volume properties. At the theoretical level the major challenge in analyzing these systems arises from the difficulty in decoupling the interactive effects of charge distribution, space constraints and molecular adsorption. At the experimental level this decoupling becomes nearly impossible. Microchannel Diffusion is an experiment capable of analyzing nanoscale confinement on molecular diffusion through simulation at the microscale. The objective of this study is to provide insight into the aforementioned decoupled interaction effects by overcoming experimental limitations specific to the nanoscale. In the absence of significant gravitational forces, micron sized particles should constitute a reliable substitute for molecules at nanoscale once the appropriate microscale channel size is determined. This substitution allows for greater control of the geometric design, size distribution, and surface modification of the diffusing constituents and decreases the complexity of quantifying the experimental results. The analysis focuses on understanding how particle and channel properties, such as surface charge, coupled with particle-to-channel interactions affect the diffusive transport. The insight into nanoscopic diffusive transport gleaned from this study are relevant for “on- Earth” applications including drug delivery, molecular sieving and particle filtration. Moreover, the study provides an understanding of microparticle diffusive transport in view of future technological applications for space exploration. The study utilizes the Light Microscopy Module (LMM) for microscopic analysis of the movement of fluorescent microparticles within a microfabricated microchannel chip (microscope slide).

^ back to top


Space Applications
Nanofluidics is the study of fluids at the nanoscale, or the atomic level, and it holds promise for a wide range of technologies. Nanofluidic sensors could measure the air in the International Space Station (ISS), or be used to deliver drugs to specific places in the body, among other potential uses. But the laws that govern flow through nanoscale channels are not well understood. This investigation simulates these interactions by studying them at a larger scale, the microscopic level. This is only possible on the ISS, where Earth’s gravity is not strong enough to interact with the molecules in a sample, so they behave more like they would at the nanoscale.

Earth Applications
Nanofluidics holds great promise for drug delivery, filtration, medical treatment, and many other uses on Earth, but scientists need a better understanding of how fluids behave at the smallest possible scales. This is difficult to study, however, because measuring atomic-scale interactions introduces errors. This investigation uses microgravity to study fluid interactions on a zoomed-out scale, providing new insight into the laws of fluid dynamics at the nanoscale.

^ back to top


Operational Requirements and Protocols

There are 4 Microchannel Diffusion plates each containing up to 12 samples. Each Microchannel Diffusion plate is imaged for up to 10 days. All 4 plates must be imaged within 6 months of being turned over to NASA for launch to the ISS. The 4 plates can be imaged on the LMM back to back or as availability of the LMM and crew time allows as long as all imaging is completed within the 6-month window. All imaging data is downlinked from the LMM on a daily basis while imaging is active. The samples are returned via ambient stowage on the next available SpaceX mission once all 4 Microchannel Diffusion plates have completed imaging requirements.

The Crew removes each Microchannel Diffusion plate from cold stowage, thaws to room temperature and inserts a data logger into a designated spot within the Microchannel Diffusion plate. The Microchannel Diffusion plate is placed on the LMM Biobase and inserted into the LMM for imaging. Imaging is started via remote commanding from NASA Glenn Research Center and lasts for up to 10 days. Once the imaging requirements are achieved, the Crew removes the Microchannel Diffusion plate from the LMM, places it in ambient stowage and loads the next Microchannel Diffusion plate onto the LMM until all 4 plates are completed.

^ back to top

Decadal Survey Recommendations

Information Pending

^ back to top

Results/More Information

Information Pending

^ back to top

Related Websites

^ back to top


Optical image of the Microchannel Diffusion device. Image courtesy of Houston Methodist Research Institute.

+ View Larger Image

image Replica of the LMM microscope used on the ISS. Image courtesy of NASA Glenn Research Center.
+ View Larger Image

Microchannel Diffusion device holder for the LMM microscope, mounting an array of 12 chips. Image courtesy of BioServe Space Technologies and Houston Methodist Research Institute.

+ View Larger Image