Microfluidic chips are normally associated with micron-scale channels and chambers. The small size of these microchannels requires the pump to provide a high upstream pressure to overcome the pressure build up. The high-pressure can cause many issues including debonding of the chips or bursting the ports in Microfluidics.
You can use this pressure drop calculator to estimate the major pressure drop in your microchannels before designing your microfluidic device. It helps to make sure 1) your chips do not get damaged due to the high pressure 2) your pump is able to provide the upstream pressure needed to run the sample through the chip. Simply enter the channel dimensions and the flow properties to estimate the pressure drop in your microfluidic channel design. Please be aware that there might be other minor pressure causing sources such as the entrance or contraction/expansion effects that are not included here. As a rule of thumb, the pressure in PDMS microfluidic chips should not exceed 200-300 kPa. However, it is recommended to design the microfluidic device such that the pressure drop does not exceed 200 kPa.