The latest development in wearable technologies has attracted much attention. In particular, collection and analysis of body fluids has been a focus. In this paper, we have reported a wearable microfluidic platform made using conventional fabric materials and laser micromachining to measure the flow rate on a patterned fabric surface, referred to as digital droplet flowmetry (DDF). The proposed wearable DDF is capable of collecting and measuring continuous perspiration with high precision (96% on average) in a real-time fashion over a defined area of skin. We have introduced a theoretical model for the proposed wearable interfacial microfluidic platform, under which various design parameters have been investigated and optimized for various conditions. The novel digitalized measurement principle of DDF provides fast responses, digital readouts, system flexibility, and continuous performance of the flow measurement. Moreover, the proposed DDF platform can be conveniently implemented on regular apparel or a wearable device, and has potential to be applied to dynamic removal, collection and monitoring of biofluids for various physiological and clinical processes.

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A simplified model to predict the performance of a novel sub-wet bulb evaporative chiller (SWEC) for producing chilled water is presented. The SWEC design uses a daisy-chained arrangement of cross-flow heat exchangers with evaporative media located in between the heat exchangers to chill water below the outdoor wet bulb temperature in either a one-pass or two-pass arrangement. Sub-models, based on the effectiveness- Number of Transfer Units method, for the heat exchanger and evaporative media are coupled together to form the SWEC model. The model is validated using field data from a SWEC that is designed with a single water pass. The model results are observed to match the SWEC experimental data within a mean average error of 0.74 percent in supply chilled water temperature and 5.6 percent in chiller capacity over a range of outdoor air dry bulb and wet bulb temperatures, and inlet water temperatures and water flow rates. The validated model is then used in a parametric study of geometrical and thermofluidic variables. The model is also used to predict the performance of the SWEC in a typical hot and dry weather over a summer week.