EXPRESS Physics of Colloids in Space (EXPPCS)
Research Area: Complex Fluids
Expedition(s): 2-4
Principal Investigator(s): ● David A. Weitz, PhD, Harvard University, Cambridge,
Massachusetts
RESEARCH OBJECTIVES
EXPRESS Physics of Colloids in Space (EXPPCS) studies the kinetics of colloidal (fine particles
suspended in a fluid) crystal formation and growth. These experiments provide the critical
information necessary to use colloidal precursors to fabricate novel materials in the new field of
colloidal engineering. Industries using semiconductors, electro-optics, ceramics, and
composites might benefit from this investigation.
EARTH BENEFITS
EXPPCS will improve such colloids as
paints, food products, drug delivery
systems and ceramics by providing a
better understanding of colloidal
behavior. The EXPPCS investigation has
contributed to Earth-based investigations
of cataracts, which are caused by the
buildup of damaged proteins within the
eye lens and are the single largest cause
of blindness. Diagnosis of cataracts is
normally carried out by looking for
protein buildup via a standard
ophthalmological device known as a slit-
lamp microscope, which can only detect
cataracts once they have formed.
Fortunately, a new laser probe originally
developed for the US space program to
study protein crystal formation on the
International Space Station (ISS), has been
shown to detect cataracts before they are symptomatic. This new technique uses dynamic light
scattering (DLS) to detect small proteins called alpha-crystalline in the eye’s lens, which is a
reliable biomarker for cataracts. Laser light is shone into the lens of the eye while a highly
sensitive photon detector is used to measure light backscattered at specific wavelengths. If the
amount of alpha-crystalline proteins has lessened, this is an indication that cataracts are
developing. If cataracts are detected early by this new technique, it may be possible to slow or
stop the accumulation of damaged proteins by reducing relevant factors.
SPACE BENEFITS
The colloidal engineering process will play a fundamental role in the creation of new materials
and products in space, such as optical switches and lasers for communications and displays.
This is one of the first images from the EXPRESS Physics
of Colloids in Space on the International Space Station.
During Expedition 2, sample AB 6 was illuminated with
white light to produce the image. The colored regions
result from refraction of the white light by the sample and
sample cell, splitting it up into its component colors. NASA
Glenn Research Center image.