A novel concept for long-term pre-storage and release of liquids for pressure-driven lab-on-a-chip devices

Abstract

On-chip storage of liquids is one of the major challenges of polymer-based lab-on-a-chip (LoC) devices. To ensure long-term storage of even highly volatile reagents in polymer disposal LoC cartridges, robust reagent storage concepts are necessary. Tubular bags, so-called stick packs, are widely used in the packaging industry. They offer sufficient vapor barrier properties for liquid storage. Here we present a polymer multilayer LoC-stack with integrated stick packs for the long-term storage of liquid reagents required for diagnostic applications. The storage concept fulfils two main requirements: firstly, the long-term storage of reagents in stick packs without significant losses or interaction with the surroundings and secondly, the on-demand release of liquids, which is realized by the delamination of a stick pack’s peel seam through pneumatic pressure. Furthermore, effects on the opening behavior of stick packs through accelerated aging were investigated after different storage conditions to proof repeatability. This concept enables on-chip storage of liquid reagents at room temperature and allows the implementation in different pressure driven LoC devices or similar applications. Since liquid storage in stick packs is well-established, emerging fields such as lab-on-a-chip combined with novel reagent release mechanisms should be of great interest for the commercialization of life science products.

Simple Approaches to Minimally-Instrumented, Microfluidic-Based Point-of-Care Nucleic Acid Amplification Tests

“…A self-contained, fully-integrated chip combining sample preparation and PCR wherein reagents were stored in separate compartments, such that they could be hydrated and then mixed with sample and transferred to an amplification reaction chamber, utilized valves fabricated into the chip and relatively complicated flow control [ 119 ]. Simpler methods proved feasible including reagent storage in sugar-based matrices [ 120 ], glass ampules [ 121 ], integrated reagents deposited by inkjet [ 122 ], including dried reagents in porous media [ 123 ], gelified reagents [ 124 ], self-contained gel capillaries [ 125 ], dissolvable films [ 126 ], microfluidic burst valves [ 127 ], and microperforated barrier films [ 128 , 129 , 130 ].…”

Polymer nanoliter well arrays for liquid storage and rapid on-demand electrochemical release

“…Table 1 compares the results of this work with those of previous work on liquid storage in microfluidic systems. Microfluidic systems with integrated blister-packs [1], stick-packs [2,3], and glass ampules [4] require pick-and-place techniques, with their associated costs, and mechanisms for pneumatic actuation or mechanical opening during operation. This limits the level of integration and hampers downscaling below volumes of several microliters.…”

“…This limits the level of integration and hampers downscaling below volumes of several microliters. Batch scale encapsulation and storage of liquid or dried sample in silicon [17,25], metallic [26], glass [4], and polymer hybrid [1][2][3]16] reservoirs enables long-term storage and often hermetic sealing, but is not compatible with polymer microfluidic integration. Sealing of polymer wells by thermal bonding [5,8] is not suitable for temperature sensitive liquids, and sealing of wells by epoxy gluing [10,16] complicates downscaling of aqueous liquid storage in multiplewell arrays.…”

“…Integrated storage and release of reagents in microfluidic platforms [1][2][3][4] enable hands-off operation and reduces the need for external interfacing. Despite previous progress [5][6][7][8][9][10], integrated encapsulation, storage and release of nanoliter to microliter volumes of aqueous solutions in polymer microfluidic devices face unresolved technical challenges.…”

Combining Electro-Osmotic Flow and FTA® Paper for DNA Analysis on Microfluidic Devices

“…The ability to store reagents within microfluidic devices offers numerous advantages, including a reduction in the complexity of the operational process, more compatibility with portable systems and a decreased risk of contamination. Reagent storage, particularly for molecular biology applications, has been demonstrated in liquid form, for example through the incorporation of stick [ 18 ] or blister packs [ 19 ], through encapsulation within gel matrices [ 12 ] or water-soluble nanofibers [ 20 ] and as freeze-dried reagents [ 21 ].…”