Interfacing caps for microfluidic devices and methods of making and using the same

A microfluidic device assembly, comprising:

• a microfluidic device having a device substrate comprising a conformal recess;
• a reagent storage vessel comprising an interfacing cap configured to interface the reagent storage vessel with the microfluidic device, and wherein the interfacing cap is configured to provide a fluid tight seal with the microfluidic device, the interfacing cap comprising:
• a partitioning element having a structure corresponding to an opening of the reagent storage vessel, wherein the partitioning element is configured to be perforated;
• a projection fitting disposed on the partitioning element, wherein the projection fitting is configured to interface the reagent storage vessel with the conformal recess of the device substrate, and wherein at least a portion of the projection fitting is configured to be disposed in the conformal recess of the microfluidic device;
• a holder element;
• and
• a puncturing element coupled to the projection fitting, wherein the puncturing element is at least partially disposed in the projection fitting, wherein the puncturing element is configured to push into the projection fitting and up to the partitioning element to perforate the partitioning element, and wherein the puncturing element is configured to form a seal with the conformal recess and transfer a reagent from the reagent storage vessel to the microfluidic device.