Microfluidic systems for epidermal sampling and sensing

A microfluidic system for measuring a characteristic of a biofluid, comprising:

• a flexible substrate;
• a collection layer embedded in or supported by the flexible substrate, wherein the collection layer is configured to promote transport of the biofluid from a skin surface;
• at least one reservoir chamber embedded in or supported by the flexible substrate and fluidically connected to the collection layer, the at least one reservoir chamber having:
• an absorbent provided to receive at least a portion of the biofluid from the collection layer;
• and
• a sensor for measuring the characteristic of the biofluid received by the absorbent;
• wherein the absorbent provides a force for transporting the biofluid that is greater than a capillary force of the collection layer for transporting the biofluid;
• a disposable portion comprising a microfluidic network and a reusable portion corresponding to an electronic device, wherein the disposable portion and the reusable portion are connected to each other by one or more selectively releasable coupling elements, wherein the selectively releasable coupling elements comprise a magnet;
• and
• a protective layer embedded in or supported by the flexible substrate, wherein the protective layer is configured to prevent the biofluid from escaping from the at least one reservoir chamber.