Primary surface measurement reported
Chapter 3 reports droplet contact angle in the electrowetting system, showing 133° in the unwetted state and 15° at 3.6 V DC in the wetted state.
Client Citation Analysis
Polyethylene-based Microfluidic System Approaches to Achieve Adaptive Visible and Thermal Camouflage Applications
This thesis develops polyethylene-based microfluidic camouflage systems and, in Chapter 3, uses a Droplet Lab smartphone-based tensiometer to quantify contact-angle change during low-voltage electrowetting for adaptive infrared camouflage.
At-a-Glance Summary
Dropometer attribution in the paper
The equipment list names the instrument as “A digital tensiometer setup (Smartphone-based tensiometer, Droplet Lab Instrument, Canada),” used for accurate measurement and monitoring of the droplet.
How the surface-tension / contact-angle data were used in the study
The contact-angle data were used to characterize DC electrowetting performance in Configuration 1. Interfacial tension also appears in the Lippmann–Young model and in the surfactant rationale used to lower activation voltage, and the device’s variable IR appearance experiments are run separately in planar electrode configurations (Configurations 3 and 4), where wetting is tracked as droplet coverage and apparent temperature with a thermal camera.
Replication / reliability statement
Figure 13 states that the wetting process is fully repeatable.
Paper Details
Title
Polyethylene-based Microfluidic System Approaches to Achieve Adaptive Visible and Thermal Camouflage Applications
Authors
Xiaoruo Sun
Institution
University of Alberta (Master of Science thesis, Department of Mechanical Engineering)
Year
2023
What Was Measured
Primary surface / interfacial measurement
The primary surface measurement reported in Chapter 3 is droplet contact angle during electrowetting. The chapter also frames the behavior through the Lippmann–Young equation, where interfacial tension, σlv, appears as a model parameter.
Supporting measurements
Capacitance was measured to estimate the thickness of the self-assembled lipid bilayer. Visible-appearance and infrared-appearance tests were also used to track droplet coverage, apparent temperature, and actuation behavior during electrowetting.
Contact angle / droplet monitoring
Digital tensiometer setup (Smartphone-based tensiometer, Droplet Lab Instrument, Canada)
IR characterization
Thermal Imaging Camera (E75, Teledyne FLIR LLC, US)
IR heat source
3D printer heating bed (Ender 3, Creality 3D, China)
Voltage application
Direct current power supply (LWK605D, LONGWEI, China)
Visible appearance imaging
Digital camera (iPhone 13 Pro Max, US)
Capacitance measurement
Digital multimeter (U1252B, Agilent Technologies, US)
Configuration / characterization support
Analytical electronic balance (ZQ-563, BAOSHISHAN, China)
Role of the Dropometer
The thesis uses a digital tensiometer setup, cited as “A digital tensiometer setup (Smartphone-based tensiometer, Droplet Lab Instrument, Canada),” for direct observation of the electrowetting droplet in Configuration 1. The paper states that it was used for accurate measurement and monitoring of the droplet, that droplet images were captured by the embedded smartphone while the droplet was applied by the default threaded plunger syringe, and that the contact angle change upon wetting was determined using the digital tensiometer.
Within the chapter workflow, this contact-angle readout provides the wetting comparison between the unwetted and voltage-actuated droplet states used to characterize electrowetting performance for adaptive infrared camouflage.
Bring This Measurement Into Your Lab
If you measure contact angle changes in electrowetting systems, we can show you the same droplet imaging workflow on your samples.
Key Findings
Large contact-angle shift
The central Dropometer-derived result is the change in droplet contact angle from 133° in the unwetted state to 15° at 3.6 V DC in the wetted state. Figure 13 presents this side-by-side comparison and states that the wetting process is fully repeatable.
Low-voltage electrowetting behavior
The thesis presents the device as a low-voltage electrowetting system, with nearly complete wetting reached at 3.6 V DC. The chapter also states that this voltage is much lower than what is observed in conventional electrowetting systems.
Surfactants integrated into the wetting strategy
The water droplet contained 3 wt% SDS and the ambient dodecane phase contained 0.8 wt% sorbitan trioleate. The thesis states that SDS was added to the water to reduce activation voltage by lowering surface tension, and that the inclusion of surfactants decreased σlv significantly.
Thin dielectric interpretation
Capacitance measurements were used to calculate a lipid bilayer thickness of 4.928 nm. The chapter uses this result to support the interpretation that a very thin dielectric layer enables low-voltage actuation.
Wetting linked to IR appearance control
In the IR experiments, the droplet coverage increased upon wetting and the apparent temperature changed markedly when the droplet covered the reflective electrode. The thesis reports an average wetting actuation time of 1.00 ± 0.33 s and presents the electrowetting system as capable of adaptive infrared camouflage.
Figures & Visuals
What it shows
Figure 11 schematically shows Configuration 1, including the stainless-steel syringe tip, metalized polyester electrode, water/SDS droplet, and dodecane with sorbitan trioleate used for the contact-angle experiment.
What it shows
Figure 13 is the primary Dropometer-linked result, showing the droplet at 133° in the unwetted state and 15° after actuation at 3.6 V DC.
What it shows
Figure 14 illustrates the droplet–electrode interface used in the chapter’s capacitance-based interpretation of the lipid bilayer and aluminum oxide layers.
What it shows
Figure 16 shows how electrowetting changes droplet coverage and reflected infrared appearance in the device configurations developed for adaptive IR camouflage.
Why It Matters
Chapter 3 is framed around the feasibility of a low-voltage electrowetting device for adaptive infrared camouflage. In that context, the Dropometer-derived contact angle is the direct wetting metric used to show that the droplet moves from a hydrophobic state to nearly complete wetting under a small applied DC voltage.
The infrared experiments then use separate planar electrode configurations (Configurations 3 and 4) imaged with a thermal camera. As the droplet spreads over the reflective electrode, the chapter uses the resulting coverage and apparent-temperature change to demonstrate variable IR appearance in the electrowetting system.
Practical Takeaways
Quoted Droplet Lab attribution
The equipment section credits the instrument as “A digital tensiometer setup (Smartphone-based tensiometer, Droplet Lab Instrument, Canada)” for droplet measurement and monitoring.
Direct wetting readout
The Dropometer-supported output used in the chapter is contact angle, with the electrowetting comparison reported as 133° in the unwetted state and 15° at 3.6 V DC in the wetted state.
Exact fluid system used
The contact-angle workflow uses a water droplet containing 3 wt% SDS in dodecane containing 0.8 wt% sorbitan trioleate on a metalized polyester electrode.
Imaging workflow described by the authors
The thesis states that droplet images were captured by the embedded smartphone while the droplet was applied by the default threaded plunger syringe.
Bilayer formation conditions
The paper specifies that sorbitan trioleate concentration must be over 0.1 wt% and that the water droplet must be applied after the electrode is submerged in dodecane.
Application fit in the study
In this work, the contact-angle measurement supports the development and characterization of a low-voltage electrowetting system for adaptive infrared camouflage.
Frequently Asked Questions
What did the Droplet Lab instrument measure in this thesis?
In Chapter 3, a Droplet Lab smartphone based tensiometer was used to image and measure the contact angle of a water droplet containing 3 wt% SDS on metalized polyester, submerged in dodecane with 0.8 wt% sorbitan trioleate. The droplet stayed in contact with a vertical needle so that a DC voltage could be applied across the droplet and the electrode.
What contact angle change was reported?
The thesis reports a contact angle of 133° with no applied voltage and 15° with 3.6 V DC applied, which the author describes as nearly complete wetting (Figure 13). The author states that the wetting process is fully repeatable and that this voltage is much lower than in conventional electrowetting systems.
What does the result mean for the camouflage application?
The author names a thin lipid bilayer that forms at the interface, estimated from capacitance at 4.928 nm, as one of the main reasons for the low actuation voltage, and links the larger droplet coverage on wetting to changes in apparent infrared temperature. The contact angle values come from Configuration 1; the infrared tests used separate configurations with planar electrodes and were recorded with a thermal camera rather than the tensiometer.