Electro-actuated valves and self-vented channels enable programmable flow control and monitoring in capillary-driven microfluidics

Abstract

Microfluidics are essential for many lab-on-a-chip applications, but it is still challenging to implement a portable and programmable device that can perform an assay protocol autonomously when used by a person with minimal training. Here, we present a versatile concept toward this goal by realizing programmable liquid circuits where liquids in capillary-driven microfluidic channels can be controlled and monitored from a smartphone to perform various advanced tasks of liquid manipulation. We achieve this by combining electro-actuated valves (e-gates) with passive capillary valves and self-vented channels. We demonstrate the concept by implementing a 5-mm-diameter microfluidic clock, a chip to control four liquids using 100 e-gates with electronic feedback, and designs to deliver and merge multiple liquids sequentially or in parallel in any order and combination. This concept is scalable, compatible with high-throughput manufacturing, and can be adopted in many microfluidics-based assays that would benefit from precise and easy handling of liquids.

Rapid quantitative assays for glucose-6-phosphate dehydrogenase (G6PD) and hemoglobin combined on a capillary-driven microfluidic chip

“…The flow is driven completely by capillarity and controlled by microfluidic structures previously developed by our group. [50][51][52][53]…”

Evaporation Induced Spontaneous Micro‐Vortexes through Engineering of the Marangoni Flow

“…Combing the traditional microfluidic technology, these vortex flows will allow many applications that are hard to achieve before. For example, by opening part of the flow channel to form an air‐liquid surface, the Marangoni flow can be introduced in the system, which has many applications in micro‐reaction control, [1] structural material synthesis [2] and reagent delivery [1–3, 21, 22] . Moreover, combing the evaporation induced assembly, the vortex flow will be promising for assembling novel structural of particles and fabricating functional devices [36, 37] …”

Capillary Microfluidics for Monitoring Medication Adherence

“…A key question is whether capillary microfluidics can integrate more advanced functions to perform assays involving reagents, various reaction times, washing steps beyond the initial principles provided by lateral flow assay formats. Despite not requiring power and incorporating passive elements, numerous functions can be performed by using, for example, capillary valves, flow resistances, self‐coalescence modules, and capillary pumps, Figure 6 a [9, 92] . A “one step assay” where only a small volume of sample needs to be loaded to a capillary microfluidic device for detecting analytes using a chemiluminescence immunoassay is shown in Figure 6 b [93] .…”