Abstract
The integration of actuators within disposable lab-on-a-chip devices is a demanding goal that requires reliable mechanisms, systematic fabrication procedures and marginal costs compatible with single-use devices. In this work an affordable 3D printed prototype that offers a compact and modular configuration to integrate actuation in autonomous lab-on-a-chip devices is demonstrated. The proposed concept can handle multiple step preparation protocols, such as the enzyme-linked immunosorbent assay (ELISA) configuration, by integrating reagents, volume metering capabilities with performance comparable to pipettes (e.g. 2.68% error for 5 μL volume), arbitrary dilution ratio support, effective mixing and active control of the sample injection. The chosen architecture is a manifold served by multiple injectors ending in unidirectional valves, which exchange a null dead volume when idle, thus isolating reagents until they are used. Functionalization is modularly provided by a plug-in element, which together with the selection of reagents can easily repurpose the platform to diverse targets, and this work demonstrates the systematic fabrication of 6 injectors/device at a development cost of USD$ 0.55/device. The concept was tested with a commercial ELISA kit for tumor necrosis factor (TNF), a marker for infectious, inflammatory and autoimmune disorders, and its performance satisfactorily compared with the classical microplate implementation.
Highlights
The integration of actuators within disposable lab-on-a-chip devices is a demanding goal that requires reliable mechanisms, systematic fabrication procedures and marginal costs compatible with single-use devices
Attempts at integrated immunoassays, such as enzyme-linked immunosorbent assay (ELISA), in lab on a chip (LOC) format have relied on demanding architectures that required specialized fabrication facilities, and modifications of the familiar protocol used with microplates[3,8,10]
In contrast with those strategies, the current concept aims at respecting as close as possible the standard procedure of exposure-incubation-washing of the conventional ELISA, in order to facilitate a direct migration of the numerous ELISA chemistries commercially available[15]
Summary
The integration of actuators within disposable lab-on-a-chip devices is a demanding goal that requires reliable mechanisms, systematic fabrication procedures and marginal costs compatible with single-use devices. The proposed concept can handle multiple step preparation protocols, such as the enzyme-linked immunosorbent assay (ELISA) configuration, by integrating reagents, volume metering capabilities with performance comparable to pipettes (e.g. 2.68% error for 5 μL volume), arbitrary dilution ratio support, effective mixing and active control of the sample injection. A key goal for any autonomous LOC concept is to support multiple step protocols, and a representative example of such situation is the classical enzyme linked immunosorbent assay (ELISA12,13), one of the most important formats of bioassays[14]. A field deployable version of such concept, or any protocol of equivalent complexity, should simplify the procedure, integrate volume metering, isolate all reagents from the environment, integrate the reagents within the device, accept modular functionalization, and eliminate auxiliary consumables
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