Ilyin, D. | Search bioRxiv

bioRxiv2025

A Microneedle Device for Rapid Dermal Interstitial Fluid Sampling

Dermal interstitial fluid (ISF) offers a promising alternative to invasive blood tests and opportunities for novel skin diagnostics. Progress in both the understanding and adoption of ISF tests is hindered by sampling challenges, including lengthy collection times, non-negligible failure rates, variable collection volumes, and inconsistent bioanalyte levels. The causes of many of these issues are not well understood. We demonstrate a microneedle device that is several times faster than state-of-the-art, collecting an average of 15.5 mg of ISF in 5 minutes in humans with near-zero failure rate. This improvement was achieved by designing the spatial pressure gradient driving ISF flow. The influence of penetration depth, collection time, pressure, and age on ISF collection was elucidated, with Darcys law explaining multiple observations. A data-driven acceptance criterion of <1% blood contamination for ISF is proposed. The device and findings presented will empower researchers to better conduct robust studies in the development of ISF diagnostics.

bioengineering↗

bioRxiv2025

Free-Form Microfluidic Microneedle Array Patches

Personalized biomedical devices, such as microneedle array patches (MAPs), offer a promising transdermal drug delivery technology, providing a safe, painless, and self- administered alternative to traditional hypodermic injections. Despite their potential for precise therapeutic release, MAP adoption has been limited by challenges in payload capacity, treatment versatility, and manufacturing scalability. To address these issues, we integrated microfluidic channel designs with MAP technology, enhancing its functionality for delivering a range of payloads, from liquid therapeutics to solid-state cargos, at tunable volumes. Using injection continuous liquid interface production (iCLIP), a novel additive manufacturing approach, we fabricated high-resolution microfluidic MAPs with complex designs. Inspired by the stingers and fangs of various venomous animals, we developed a biomimetic microneedle design that prevents clogging, enhances mechanical strength, and eliminates needle leakage, thereby improving therapeutic delivery efficiency. Our technology reliably delivers multiple distinct payloads, enables combinational mixing, and enables point-of-care reconstitution of solid-state payloads. TeaserLeveraging biomimetic design and advanced 3D printing, we developed high-resolution microfluidic microneedle array patches (MAPs) that overcome payload and scalability challenges, offering a versatile and efficient platform for precise transdermal drug delivery.

bioengineering↗