Drug delivery:Controlling the flow
http://www.100md.com
One of the challenges facing drug delivery is to achieve a constant, steady dose of a drug instead of the large, sudden doses generated with pills. New silicone rubber devices with specially shaped microscopic channels could open up new possibilities for medicine-delivering implants, according to Stephen Quake and colleagues in the 9 May issue of Science. The researchers created two miniature fluid devices, one to control the liquid-flow rate and the other for fluidic memory, both of which rely on the special behaviour of polymer liquids to function.
In a throw back from the 1960s and 1970s when fluidic circuit research was overtaken by silicon-based electronics, in part because fluidic circuits could not be miniaturized easily, amazing advances in microfluidics now present the possibilities of giant robotic biochemical workstations being replaced by an entire lab-on-a-chip.
The flow control device is called a flux stabilizer, which is analogous to an electronic constant-current source, and it can deliver a constant rate of liquid discharge despite changing driving pressure. The dissolved polymer molecules make the liquid thick and resistant to movement above a particular flow rate, thereby stabilizing the flow output at a well-defined value. The present experiments used polyacrylamide, but the use of other polymers, such as DNA, should have the same result. Groisman et al. also used the nonlinear properties of polymers and an innovative fluid chamber design to construct a fluidic memory device called a flip-flop, which is analogous to a digital flip-flop memory. The tiny fluid gadget can maintain a ’high’ or ’low’ state of either pressure or flow rate, storing information as ones and zeroes, as in electronic memory.
Although only pilot devices have been built so far, one can imagine an implanted pill or a miniature intravenous drip with an inflatable chamber to hold a drug. If this reservoir was connected to the microfluidic flux stabilizer, a relatively constant flow of medicine could be achieved despite decreases in driving pressure as the chamber empties.
References
ORIGINAL RESEARCH PAPER
Groisman, A., Enzelberger, M. & Quake, S. R. Microfluidic memory and control devices. Science 300, 955–958 (2003), http://www.100md.com
In a throw back from the 1960s and 1970s when fluidic circuit research was overtaken by silicon-based electronics, in part because fluidic circuits could not be miniaturized easily, amazing advances in microfluidics now present the possibilities of giant robotic biochemical workstations being replaced by an entire lab-on-a-chip.
The flow control device is called a flux stabilizer, which is analogous to an electronic constant-current source, and it can deliver a constant rate of liquid discharge despite changing driving pressure. The dissolved polymer molecules make the liquid thick and resistant to movement above a particular flow rate, thereby stabilizing the flow output at a well-defined value. The present experiments used polyacrylamide, but the use of other polymers, such as DNA, should have the same result. Groisman et al. also used the nonlinear properties of polymers and an innovative fluid chamber design to construct a fluidic memory device called a flip-flop, which is analogous to a digital flip-flop memory. The tiny fluid gadget can maintain a ’high’ or ’low’ state of either pressure or flow rate, storing information as ones and zeroes, as in electronic memory.
Although only pilot devices have been built so far, one can imagine an implanted pill or a miniature intravenous drip with an inflatable chamber to hold a drug. If this reservoir was connected to the microfluidic flux stabilizer, a relatively constant flow of medicine could be achieved despite decreases in driving pressure as the chamber empties.
References
ORIGINAL RESEARCH PAPER
Groisman, A., Enzelberger, M. & Quake, S. R. Microfluidic memory and control devices. Science 300, 955–958 (2003), http://www.100md.com