Automation of Serial Dilution using Microfluidic Digital Logic

Fluid handling procedures like serial dilution are common to a number of laboratory protocols. Such procedures are time consuming and require laboratory training to be performed. Thus using microfluidics technology for such procedures is very promising. Whereas there are a number of innovative lab-on-a-chip systems that use microfluidics to miniaturize lab procedures, these devices require heavy off-chip equipments to operate. For example a typical setup consists of a pump, a computer, tons of tubing and more. Such dependency on off-chip machinery limits microfluidic liquid handling devices only to highly-equipped settings. Therefore to exploit the microfluidic technology such that the devices are also useful for limited resource settings and other applications (e.g. point-of-care diagnostics), it is important to minimize or eliminate the dependence of these devices on off-chip control equipments. Automation of fluid-handling microfluidic devices can be achieved by incorporating the control logic in the chip design. Pneumatic digital logic structures can be built on the chip and can be used to provide timing reference and also control signals for operations such as mixing/diluting, selection, storage and routing of liquid on the chip. This project explores the usefulness of pneumatic digital logic for the purpose of automation of fluid handling microdevices. Serial dilution, which is a very common laboratory procedure, is automated on-chip such that the chip requires only one constant vacuum source for power and one clock signal to operate. Logic circuits such as the microfluidic oscillator, the finite state machine and, decoding circuits are employed to automate a fluid-handling circuit on the chip. This report discusses how these pneumatic digital logic structures can be integrated and optimized in order to control and operate a fluid-handling structure that carries out on-chip serial dilution