Strain-Tunable Microfluidic Devices with Crack and Wrinkle Microvalves for Microsphere Screening and Fluidic Logic Gates

Abstract

Mechanical instabilities in soft materials have led to the formation of unique surface patterns such as wrinkles and cracks for a wide range of applications that are related to surface morphologies and their dynamic tuning. Here, we report a simple yet effective strategy to fabricate strain-tunable crack and wrinkle microvalves with dimensions responding to the applied tensile strain. The crack microvalves initially closed before stretching are opened as the tensile strain is applied, whereas the wrinkle microvalves exhibit the opposite trend. Next, the performance of crack and wrinkle microvalves is characterized. The design predictions on the bursting pressure of microvalves and others from the theory agree reasonably well with the experimental measurements. The microfluidic devices with strain-tunable crack and wrinkle microvalves have then been demonstrated for microsphere screening and programmable microfluidic logic devices. The demonstrated microfluidic devices complement the prior studies to open up opportunities in microparticle/cell manipulations, fluidic operations, and biomedicine.

Electrochemically Controlled Reversible Formation of Organized Channel Arrays in Nanoscale-Thick RuO2 Films: Implications for Mechanically Stable Thin Films and Microfluidic Devices

“…The ability to open and close channels and control channel widths by controlling the state of charge also demonstrates a new electrochemical approach for making dynamically adjustable channel arrays for microfluidic, sensor, or other applications. Although controlled cracking has been used in microfluidic devices in previous studies using different materials and different actuation mechanisms, , our system offers a way to open and close channels without applying external strains. If coated with a stretchable electrolyte, such as a polymer electrolyte, opening and closing the crack patterns could be used to electrochemically control flow or as a valve in microfluidic devices.…”

Wrinkled Interfaces: Taking Advantage of Anisotropic Wrinkling to Periodically Pattern Polymer Surfaces

“…Other than those successful applications of oriented wrinkled interfaces depicted above, they have been employed for different [283] Copyright 2021, American Chemical Society.…”

“…More recently, controlled wrinkling can be applied as an alternative patterning tool to fabricate microfluidics. [ 282 , 283 , 284 , 285 ] Liu et al. fabricated strain‐tunable crack and oriented wrinkle microvalves for microfluidic devices, as depicted in Figure 27 .…”

“…These microfluidic devices have been demonstrated for microsphere screening (Figure 27b ) and programmable microfluidic logic devices (Figure 27c ). [ 283 ]…”

Design of protective and high sensitivity encapsulation layers in wearable devices

“…At the skindevice interface, physiological processes like sweat, meta-bolites, and secretion create a complex operational environment for bare pressure sensors that degrade their performance. Therefore, a soft, elastomeric encapsulation layer with low water permeability is typically used to mitigate the effects of skin physiological processes in the device, such as chemical corrosion and device failure [11][12][13][14][15]. Further, the elastomeric encapsulation layer protects the pressure sensor from large mechanical deformations (socalled strain-and stress-isolation) [2,16,17] while in operation and facilitates assembly with other electronics components in the wearable device.…”