Bioengineers Design Device to Help Detect Diseases Quickly
August 23, 2010 – 9:26 pm
Researchers at Arizona State University have demonstrated a way to simplify testing patients for infectious diseases and unhealthy protein levels. New testing instrumentation developed by professors Antonia Garcia and John Schneider could make the procedure less costly and produce results in less time.
Current testing is slow and expensive because of the complications of working with blood, saliva, urine and other biological fluids, says Garcia. Such samples “are complex mixtures that require sophisticated instruments capable of mixing a sample with antibodies or other biological reactants to produce an accurate positive or negative reaction,” Garcia says.
He and Schneider, a bioengineering graduate student researcher, have devised a testing method that enables the patient sample itself to act in concert with a rudimentary, low-cost testing device.
The method uses common light-emitting diodes (LEDs) and simple microeletronic amplifiers rather than more technologically intensive and costly lasers and robotics.
Fluids and light working together
Garcia and Schneider have demonstrated that superhydrophobic surfaces can shape blood, saliva, urine and other fluids into round drops. The drops can focus light and quickly mix and move microparticles and nanopartices that can be examined to reveal a specific infectious agent or protein.
Superhydrophobicity is a property of materials that repel water, such as ducks’ feather or leaves of the lotus plant. Such materials are used commercially in textiles, building materials and surface coatings.
The new device operates by placing a drop of nanoparticles or microparticles on top of a drop of a patient fluid sample on a superhydrophobic surface. The surface has a small depression that holds the liquid sample in place so that it forms a spherical drop.
The drop acts as a lens due to surface tension. An LED is shined on the drop and the drop shape focuses the light into an intense beam measured by a second LED.
Because the drop is slowly evaporating, Garcia explains, nanoparticles or microparticles quickly begin to stick together when the patient fluid sample contains the infectious agent or protein being targeted. The infectious agent or protein migrates to the center of the drop, leaving the particles that have not yet stuck together to move to the surface.
This leads to the self-mixing action that speeds up the diagnostic process so that detection can occur in less than two minutes, he said.
Measuring overall health
Because the fluid sample becomes integrated with the simple LEDs and microelectronics, the researchers call the new device design the Integrascope.
Garcia and Schneider have built several laboratory prototype devices based on the design and have demonstrated how the device can be used to measure C Reactive Protein in human serum, which is an indicator of a variety of inflammatory conditions when the protein is present at high levels.
High levels of protein can indicate cell and tissue damage, inflammation, disruption in kidney function, or an immune system that is pumping out antibodies due to an infection or autoimmune disease. Low protein levels can indicate malnutrition or the presence of diseases that prevent the body from producing sufficient blood protein.
The device also can be used to provide an indication of overall health by measuring total protein in human serum, saliva and urine.
More information on the research is available from Arizona State University.
Tags: Arizona State University, bioengineers, LEDs, nanoparticles
