Abstract

Roll-to-Roll UV-Imprinting for Microfluidic Burst Valve in Microsampling Devices

Laura Angermann-Krammer, Scientist, Joanneum Research

Although central testing is still the gold standard (as we experience in the current pandemic for PCR), it requires the patients to visit the clinics or doctor offices for sample collection, which might be inconvenient, is often costly, takes longer and increases the risk of spreading the disease. Therefore, remote microsampling is seen as the key to transform the in vitro diagnostics field and market, since it (i) provides easier access to rural areas and low-middle income countries, (ii) makes life easier for pediatric, elderly and patients with chronic conditions and (iii) minimizes the risk of spreading infectious diseases. Accordingly, the Biosensors Group (KU Leuven) has developed a microfluidic sampling device for volumetric dried blood spot (DBS) collection, exploiting the self-powered (i)SIMPLE technology as passive driving source to first isolate a precise sample volume from a finger-pricked capillary blood sample and subsequently load it on pre-cut filter papers [1, 2]. Precise volume metering is realized by the coordinated burst action of hydrophobic burst valves (HBVs). However, to bring this solution successfully to the market, high-throughput and cost-effective chip manufacturing is of utmost importance. Hereto, the potential of ultraviolet light-assisted nanoimprinting (UV-NIL) was explored as a readily scalable roll-to-roll (R2R) manufacturing technique for the automated production of the microsampling chips [3]. Instead of using HBVs, requiring local patterning of hydrophobic regions within the chip, geometric burst valves (GBVs) were introduced, which like HBV introduce local flow resistances but by means of abrupt changes in channel width. GBVs benefit from the high resolution of the exploited UV-NIL technique, which is essential, as the burst pressure is strongly affected by the channel geometry and surface tension as described by the Young-Laplace equation. The mastering of the GBV structures was done via contact photolithography. The micros