Posted by: Bystander PJ12 AUG 2009
On the University of Michigan website there is a video clip showing microscopic drops of coloured liquid moving jerkily across the screen in time with the notes of a computer-generated version of the jingoistic football song sung by Michigan Wolverines supporters.
The video clip is there to illustrate research findings in the university’s engineering department. The researchers have found a way of using musical notes to control the movement of fluids through “lab-on-a-chip” devices.
Their goal is to use the technology to develop a gadget “the size of an iPhone” that can perform tasks such as diagnosing influenza from a well-directed sneeze.
(Do you remember the days when an object that fitted into the palm of the hand would be compared in size to a cigarette packet? How the world moves on.)
The term “lab-on-a-chip” describes a microfluidic device that combines a number of laboratory functions on a single chip — perhaps just millimetres in size — so that researchers can perform different tests on the same tiny sample of material. Such devices could lead to instant home tests for medical conditions, food contamination, toxic gases, etc.
But a problem with microfluidic systems is that moving, mixing and splitting pin-prick drops of fluid in the device’s microscopic channels may require dozens of air hoses, valves and electrical connections between the chip and a computer, thus reducing the advantages one might expect from small-scale applications.
What the Michigan researchers have developed is a simple device using sound waves to drive a pneumatic system that does not need electromechanical valves. Instead, musical notes produce the air pressure to control droplets of fluid within the device.
The hoses, valves and electrical connections are replaced by tiny resonance cavities, each connected at one end to channels in the microfluidic device and at the other to a computer-controlled speaker. Each resonance cavity is designed to amplify a specific musical tone, generating a sound wave that nudges the fluid droplet into its assigned channel.
The new system is still external to the chip, but the researchers hope to reduce its size to fit on a microfluidic device. The home flu test kit that fits the palm of your hand could be a reality before long.