Microfluidic systems, devices and methods for reducing diffusion and compliance effects at a fluid mixing region

A method for fabricating a microfluidic device having waste channels, the method comprising:

• (a) providing a substrate;
• (b) forming a fluid mixing region in the substrate, the fluid mixing region including an inlet for receiving fluids for mixing;
• (c) forming a first microscale channel in the substrate, the first microscale channel including an end connected to the inlet for advancing a first fluid to the mixing region;
• (d) forming a second microscale channel in the substrate, the second microscale channel including an end connected to the inlet for advancing a second fluid to the mixing region;
• (e) forming a first waste channel in the substrate, the first waste channel connected to the end of the first microscale channel for removing the second fluid diffused into the end of the first microscale channel;
• and
• (f) forming a second waste channel in the substrate, the second waste channel connected to the end of the second microscale channel for removing the first fluid diffused into the end of the second microscale channel.

A method for controlling the flow of fluids into a fluid mixing region, the method comprising:

• (a) providing a microfluidic device, comprising:
• (i) a microfluidic chip including first and second microscale channels having ends connected at a junction for advancing a first and second fluid, respectively, to the junction for mixing;
• and
• (ii) a first pump connected to the first microscale channel and operable to advance the first fluid through the first microscale channel to the junction;
• and
• (b) controlling the first pump to hold the first fluid in position no greater than a predetermined time period before advancing the first fluid to the junction.