Coupling biological materials with an electrode-based device, Prof. Judith Rishpon of TAU’s Department of Molecular Microbiology and Biotechnology is able to quickly and precisely detect pathogens and pollution in the environment – and infinitesimally small amounts of disease biomarkers in our blood. About the size of a stick of gum, the new invention may be applied to a wide range of environments and situations. The aim is for the device to be disposable and cost about $1.
What makes this particular invention particularly appealing is its small size and the fact that it can be easily connected to a handheld device like a Blackberry or iPhone for quick and reliable results.
While traditionally only a few chemical reactions could be produced on a chip, the research team pioneered a way to instigate multiple reactions, thus offering a new method to quickly screen which drug molecules may work most effectively with a targeted protein enzyme. In this study, scientists produced a chip capable of conducting 1,024 reactions simultaneously, which, in a test system, ably identified potent inhibitors to the enzyme bovine carbonic anhydrase.
A thousand cycles of complex processes, including controlled sampling and mixing of a library of reagents and sequential microchannel rinsing, all took place on the microchip device and were completed in just a few hours. At the moment, the UCLA team is restricted to analyzing the reaction results off-line, but in future, they intend to automate this aspect of the work as well.
To do an experiment in a microfluidic device today, researchers often use dozens of air hoses, valves and electrical connections between the chip and a computer to move, mix and split pin-prick drops of fluid in the device’s microscopic channels and divots.
“You quickly lose the advantage of a small microfluidic system,” said Mark Burns, professor and chair of the Department of Chemical Engineering and a professor in the Department of Biomedical Engineering.
“You’d really like to see something the size of an iPhone that you could sneeze onto and it would tell you if you have the flu. What hasn’t been developed for such a small system is the pneumatics—the mechanisms for moving chemicals and samples around on the device.”
The U-M researchers use sound waves to drive a unique pneumatic system that does not require electromechanical valves. Instead, musical notes produce the air pressure to control droplets in the device. The U-M system requires only one “off-chip” connection.
“This system is a lot like fiberoptics, or cable television. Nobody’s dragging 200 separate wires all over your house to power all those channels,” Burns said. “There’s one cable signal that gets decoded.”
The system developed by Burns, chemical engineering doctoral student Sean Langelier, and their collaborators replaces these air hoses, valves and electrical connections with what are called resonance cavities. The resonance cavities are tubes of specific lengths that amplify particular musical notes.
These cavities are connected on one end to channels in the microfluidic device, and on the other end to a speaker, which is connected to a computer. The computer generates the notes, or chords. The resonance cavities amplify those notes and the sound waves push air through a hole in the resonance cavity to their assigned channel. The air then nudges the droplets in the microfluidic device along.
“Each resonance cavity on the device is designed to amplify a specific tone and turn it into a useful pressure,” Langelier said. “If I play one note, one droplet moves. If I play a three-note chord, three move, and so on. And because the cavities don’t communicate with each other, I can vary the strength of the individual notes within the chords to move a given drop faster or slower.”