Chronic wounds affect over 6.5 million Americans and are notoriously difficult to treat. Suboptimal oxygenation of the wound bed is one of the most critical and treatable wound management factors, but existing oxygenation systems do not enable concurrent measurement and delivery of oxygen in a convenient wearable platform. Thus, we developed a low-cost alternative for continuous O₂ delivery and sensing comprising of an inexpensive, paper-based, biocompatible, flexible platform for locally generating and measuring oxygen in a wound region. The platform takes advantage of recent developments in the fabrication of flexible microsystems including the incorporation of paper as a substrate and the use of a scalable manufacturing technology, inkjet printing. Here, we demonstrate the functionality of the oxygenation patch, capable of increasing oxygen concentration in a gel substrate by 13% (5 ppm) in 1 h. The platform is able to sense oxygen in a range of 5–26 ppm. In vivo studies demonstrate the biocompatibility of the patch and its ability to double or triple the oxygen level in the wound bed to clinically relevant levels.

Gut microbiota plays an important role in host physiology such as obesity, diabetes, and various neurological diseases. Thus, microbiome sampling is a fundamental approach towards better understanding of possible diseases. However, conventional sampling methods, such as endoscopies or colonoscopies, are invasive and cannot reach the entire small intestine. To address this need, a battery-less 3D-printed sampling capsule, which can collect microbiome samples throughout the entirety of the GI tract was designed. The capsule (9 mm × 15 mm) consists of a 3D printed acrylic housing, a fast-absorbing hydrogel, and a flexible PDMS membrane. Fluids containing samples of the microbial flora within the GI tract enter the device through a sampling aperture on the cap of the device. Once the microbiome enters the housing, the hydrogel absorbs the fluid and swells, effectively protecting the samples within its polymeric matrix, while also pushing on the flexible PDMS membrane to block the sampling aperture from further fluid exchange. The retrieved capsule can be readily disassembled due to the screw-cap design of the capsule and the hydrogel can be removed for further bacterial culture and analysis. As a proof of concept, the capsule's bacterial sampling efficiency and the ability to host microbial samples within the hydrogel in a sealed capsule were validated using a liquid culture containing Escherichia coli. The demonstrated technology provides a promising inexpensive tool for direct sampling and assessment of microbes throughout the GI tract and can enable new insights into the role of diet in mediating host–microbe interactions and metabolism.

This work presents a low-cost, passive, flexible, polymeric pump for topical drug delivery which uses wound pH as a trigger for localized drug release. Its operation relies on a pH-responsive hydrogel actuator which swells when exposed to the alkaline pH of an infected wound. The pump enables slow release (<0.1 μL min⁻¹) of aqueous anti-bacterial solution for up to 4 hours and sustains against up to 8 kPa of backpressure. Featuring a scalable layer-by-layer fabrication technique to expand the pump into a 2 × 2 array, the device can dispense 50 μl onto a 160 mm² dermal coverage within 4 hours. Robustness tests show that when integrated within a medical adhesive, the device can be worn around the forearm and can withstand various daily activities (non-intensive) for up to 12 hours. In vitro experiments demonstrate a 58 times decrease of live P. aeruginosa after 24 hours of the pump assisted antibiotics treatment.

In this paper, we present a disposable, colorimetric, user-friendly and mass-customizable dermal patch for chronological collection and discrete real-time in situ measurement of sweat secretion over a small area of skin. The patch consists of a laminated filter paper patterned into radially arranged channels/fingers with water-activated dyes at their tips. As channels are filled during perspiration, their tips change color once fully saturated, providing easily identifiable levels of water loss which in turn can be mapped to personal dehydration levels. The patch can be manufactured at low cost in a variety of sizes to allow hydration monitoring for individuals participating in activities under different conditions (intensity, temperature, humidity, etc.). Furthermore, we describe an analytical model that enables mass customization of such a flexible wearable system accommodating a broad range of sweat rates and volumes to generate patch designs that are personalized to an individual’s sweat rate, desired time of usage, and the temporal resolution of the required feedback. As a proof-of-concept demonstration, we characterized laser-fabricated patches that cover (7 cm × 5 cm) area of skin having various wicking materials, thicknesses (180–540 µm), and pore sizes (3–11 µm). Tests were conducted at various flow rates simulating different sweating intensities in the range of 1.5–15 mg/cm²/min. Experimental results for the case of a half-marathon runner targeting 90 min of usage and sweating at a rate of 1.5 mg/cm²/min indicated measurement accuracy of 98.3% when the patch is completely filled.