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Year-round ultraviolet exposure silently causes skin damage that goes unnoticed until sunburn. Current personal wearables for monitoring UV exposure have not seen significant uptake, which may be attributed to their one-size-fits-all aesthetic or inapplicability to people with different skin tones. We present EcoPatches, inkjet-printable chemical patches that mediate a person's relationship with their environment by allowing them to create designs and formulations that resonate with them. Supporting human- and machine-interpretability for EcoPatches' visual changes means that users can glance at their EcoPatch during the day to see large exposure changes or take a picture of their EcoPatch with a smartphone app for more accurate and precise readings. We conducted an online survey to elicit visual design recommendations that support these features. We also evaluated both interpretation methods, finding that they achieved strong Pearson correlation coefficients with the \projectnames' known exposure levels (human: 0.79, app: 0.90).

Microfluidic devices promise to automate wetlab procedures by manipulating small chemical or biological samples. This technology comes in many varieties, all of which aim to save time, labor, and supplies by performing lab protocol steps typically done by a technician. However, existing microfluidic platforms remain some combination of inflexible, error-prone, prohibitively expensive, and difficult to program. We address these concerns with a full-stack digital microfluidic automation platform. Our main contribution is a runtime system that provides a high-level API for microfluidic manipulations. It manages fluidic resources dynamically, allowing programmers to freely mix regular computation with microfluidics, which results in more expressive programs than previous work. It also provides real-time error correction through a computer vision system, allowing robust execution on cheaper microfluidic hardware. We implement our stack on top of a low-cost droplet microfluidic device that we have developed. We evaluate our system with the fully-automated execution of polymerase chain reaction (PCR) and a DNA sequencing preparation protocol. These protocols demonstrate high-level programs that combine computational and fluidic operations such as input/output of reagents, heating of samples, and data analysis. We also evaluate the impact of automatic error correction on our system's reliability.

We present EarthTones, cosmetic-inspired wearable chemical sensing powders to detect and display harmful environmental factors through color change. We seek to create an analog display experience through chemical reactions that overcome current constraints of rigid, battery-laden wearable displays. We designed three unique chemical changing powders to reflect elevated levels of carbon monoxide (CO), ultraviolet (UV) rays, and ozone (O3). The powders achieve color changes distinguishable to the human eye, while maintaining an aesthetic appeal to the wearer. Our technical evaluations confirmed the performance of the powders to detect and display elevated levels. An 18-person exploratory study provided insight to the perceptions, possibilities, and challenges of a powder form factor for wearable environmental visualization. Through this paper, we intend to enable the use of colorimetric chemical displays for HCI researchers and designers. More generally, we seek to encourage the research and use of chemical-based sensors and interdisciplinary research in HCI.