Abstract: Various examples are provided related to interstitial fluid (ISF) or extracellular fluid (ECF) harvesting and processing. In one example, a microfluidic monitoring platform includes a microneedle patch including microneedles on a first side; an osmotic patch on a second side of the microneedle patch that includes glycerogel or hydrogel equilibrated with glycerin or glucose; and a microfluidic or fluid transport film or material channel between the osmotic patch and the microneedle patch. The channel can extract fluid from the osmotic-microneedle patch complex. In another example, a wearable electrochemical sensing system includes a monitoring platform including a microneedle-osmotic patch, a microfluidic or fluid transport film or material channel, and at least one sensor between the channel; and processing circuitry coupled to the at least one sensor. The processing circuitry can monitor presence of a chemical or biomarker in the fluid based upon signals obtained from the sensor.