Capabilities in health monitoring via capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH and concentration of both chloride and lactate.

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Chronic non-healing wounds challenge tissue regeneration and impair infection regulation for patients afflicted with this condition. Next generation wound care technology capable of in situ physiological surveillance which can diagnose wound parameters, treat various chronic wound symptoms, and reduce infection at the wound noninvasively with the use of a closed loop therapeutic system would provide patients with an improved standard of care and an accelerated wound repair mechanism. The indicating biomarkers specific to chronic wounds include blood pressure, temperature, oxygen, pH, lactate, glucose, interleukin-6 (IL-6), and infection status. A wound monitoring device would help decrease prolonged hospitalization, multiple doctors' visits, and the expensive lab testing associated with the diagnosis and treatment of chronic wounds. A device capable of monitoring the wound status and stimulating the healing process is highly desirable. In this review, we discuss the impaired physiological states of chronic wounds and explain the current treatment methods. Specifically, we focus on improvements in materials, platforms, fabrication methods for wearable devices, and quantitative analysis of various biomarkers vital to wound healing progress.

Non-invasive treatment of injuries and disorders affecting bones and connective tissue is a significant challenge facing the medical community. A treatment route that has recently been proposed is nitric oxide (NO) therapy. Nitric oxide plays several roles in physiology with many conditions lacking adequate levels of NO. As NO is a radical, localized delivery via NO donors is essential to promoting biological activity. Herein, we review current literature related to therapeutic NO delivery in the treatment of bone, skin and tendon repair.

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Although the release of nitric oxide (NO) from biomaterials has been shown to reduce the foreign body response (FBR), the optimal NO release kinetics and doses remain unknown. Herein, polyurethane-coated wire substrates with varying NO release properties were implanted into porcine subcutaneous tissue for 3, 7, 21 and 42 d. Histological analysis revealed that materials with short NO release durations (i.e., 24 h) were insufficient to reduce the collagen capsule thickness at 3 and 6 weeks, whereas implants with longer release durations (i.e., 3 and 14 d) and greater NO payloads significantly reduced the collagen encapsulation at both 3 and 6 weeks. The acute inflammatory response was mitigated most notably by systems with the longest duration and greatest dose of NO release, supporting the notion that these properties are most critical in circumventing the FBR for subcutaneous biomedical applications (e.g., glucose sensors).

Despite clear evidence that polymeric nitric oxide (NO) release coatings reduce the foreign body response (FBR) and may thus improve the analytical performance of in vivo continuous glucose monitoring devices when used as sensor membranes, the compatibility of the NO release chemistry with that required for enzymatic glucose sensing remains unclear. Herein, we describe the fabrication and characterization of NO-releasing polyurethane sensor membranes using NO donor-modified silica vehicles embedded within the polymer. In addition to demonstrating tunable NO release as a function of the NO donor silica scaffold and polymer compositions and concentrations, we describe the impact of the NO release vehicle and its release kinetics on glucose sensor performance.

The active release of pharmaceutical agents and the use of porous sensor membranes represent the two most promising strategies for addressing the poor tissue biocompatibility of implantable glucose biosensors. Herein, we describe the combination of these approaches to create nitric oxide (NO)-releasing porous fiber mat-modified sensor membranes. An electrospinning method was used to directly modify needle-type glucose biosensors with the NO donor-loaded fibers. The resulting NO-releasing fiber mat (540 ± 139 nm fiber diameter, 94.1 ± 3.7% porosity) released ~100 nmol NO per mg polyurethane over 6 h while maintaining a porous structure without leaching of the NO donor, even in serum. The porous fiber membrane did not influence the analytical performance of the biosensor when ≤ 50 μm thick.