Primary surface measurement reported
DI water surface tension, receding contact angle, and advancing contact angle were measured under controlled temperature and relative humidity inside the chamber.
Client Citation Analysis
Design and implementation of environment chamber for interfacial phenomenon processes
This thesis develops a portable temperature- and humidity-controlled environment chamber and benchmarks it with DI water surface tension and contact-angle measurements captured using the authors’ DropletLab© smartphone workflow.
At-a-Glance Summary
Disclosure
This thesis is in-house work. Its author, Gurdeep Saini, is Droplet Lab's Chief of Operations; his supervisor, Alidad Amirfazli, is a Droplet Lab co-founder and Scientific Advisor. The thesis credits Droplet Lab designs as the basis for its imaging fixtures. It is presented here as technology background, not as independent third-party validation.
Dropometer attribution in the paper
The thesis states that a phone was used for image acquisition and image processing using the “DropletLab© sessile and pendent apps,” with ADSA-P used for surface tension and ADSA-P plus polynomial used for contact angle.
How the surface-tension / contact-angle data were used in the study
The surface-tension and contact-angle outputs were used to benchmark the chamber against literature experiments performed at defined temperature and humidity conditions. The study used them to compare trend agreement for humidity-dependent surface tension, evaporative receding contact angle on glass, and advancing contact angle on Teflon.
What the chamber can and cannot do
Operating range: 10 °C to 70 °C, ambient to 80% RH, and only "near the center of volume of the controlled environment inside the chamber, not the inner corners or edges." The device tested is a reduced-scope prototype — supply chain disruption during the pandemic forced a redesign, and the thesis states plainly that "it cannot be run to its maximum settings without failure." A test at 90 °C and 100% RH destroyed the silicone seal at the 1200-second mark. Temperature overshoot at setpoint is 1.2 °C ± 0.45; steady-state error under 1 °C. Cooling to 15 °C takes 70 minutes for the air to reach setpoint because the heat sink works against natural convection. Humidity readings fluctuate significantly above and below ambient due to constant condensation on the cooling block. All readings come from a single sensor per variable; the thesis recommends future work use "an average of multiple sensors distributed inside the chamber."
Paper Details
Title
Design and implementation of environment chamber for interfacial phenomenon processes
Authors
Gurdeep Singh Saini
Peer review
Not peer-reviewed. MASc thesis, Faculty of Graduate Studies, York University. The underlying measurement method is peer-reviewed separately in Chen, Muros-Cobos & Amirfazli, Rev. Sci. Instrum. 89, 035117 (2018).
Relationship disclosure
This thesis is in-house work. Its author, Gurdeep Saini, is Droplet Lab's Chief of Operations; his supervisor, Alidad Amirfazli, is a Droplet Lab co-founder and Scientific Advisor. The thesis credits Droplet Lab designs as the basis for its imaging fixtures. It is presented here as technology background, not as independent third-party validation.
What Was Measured
Primary surface / interfacial measurement
The thesis reports DI water surface tension by the pendent drop method and DI water contact angle by sessile-drop tests. Surface-tension benchmarking was performed at constant temperature with varied humidity, and contact-angle benchmarking covered receding behavior on glass and advancing behavior on Teflon.
Supporting measurements
Supporting measurements included chamber air temperature, Peltier temperature, ITO glass temperature, and relative humidity inside the chamber. The receding-contact-angle benchmark also tracked initial contact angle, contact angle radius, and initial volume.
Instruments Mentioned
Surface tension / contact angle image acquisition and image processing
DropletLab© sessile and pendent apps
Image capture
smart phone
Lighting
LED back light
Temperature
RTD sensors (PT100 / PT1000)
Relative humidity
SHT-30 Temperature/Humidity sensor
Chamber hardware and control electronics
Laird ETX6-12-F1-4040-TA-RT-W6 (Peltier) · Delta FHS-A9025S19 (heat sink/fan) · Elegoo MEGA 2560 (microcontroller) · Cytron MDD10A (motor driver) · Adafruit 3290/3984/3328/3648/4099 (RTDs, amplifiers, SHT-30) · SainSmart 2-channel relay · DFRobot DFR0009 (display) · AGPTEK atomizer · Dewin air pump · McMaster-Carr (heat sinks, fan, pipe) · custom PEEK, PTFE, ITO glass and acrylic parts per Appendix B drawings 1–14
Commercial chambers reviewed for comparison
Krüss TC40 · DataPhysics TFC 100Pro · DataPhysics TPC 160 · Ramé-hart Peltier chamber · Ramé-hart Advanced chamber (thesis Table 2-B)
Role of the Droplet Lab software
The thesis states that a phone was used for image acquisition and image processing, using the DropletLab© sessile and pendent apps. An LED back light was used to increase contrast so the droplet outline could be extracted accurately by the imaging software; in the surface-tension benchmark, an image of a DI water droplet sufficiently deformed by gravity was analyzed by ADSA-P, while the sessile-drop studies used ADSA-P and polynomial fits for contact-angle measurements.
The thesis used a smartphone running Droplet Lab's apps for image capture and analysis: "A phone was used for image acquisition and image processing, using the DropletLab© sessile and pendent apps." No product model is named — the string "Dropometer" does not appear in the thesis. The imaging fixtures around it (base plate, phone holder, syringe holder, LED backlight) were fabricated by the author from his own drawings in Appendix B, "adapted from the commercial product from Droplet SmartTech company in Toronto." Droplet Lab's contribution to this work is the analysis software plus the fixture designs; the chamber itself and all its control electronics are the author's.
Key Findings
40°C humidity response matched the benchmark
At 40°C, DI water surface tension decreased as relative humidity increased. The thesis states that this matched the literature trend used for benchmarking.
At 15 °C the chamber did not reproduce the published trend
The thesis states: "The results were not the same for 15°C where the trend reported by literature could not be replicated with the chamber," and its conclusion concedes "measurements taken at 15°C showed significant deviation from the literature." The recorded surface-tension values were between about 71 and 73 mN/m across the tested humidity conditions. The author argues the literature value is the error, noting the IAPWS accepted value of 73.5 mN/m ± 0.4 and that 78 mN/m requires water supercooled to −16.5 °C. That argument may well be right.
Glass evaporation stayed pinned
For DI water on glass at 27.5°C and 61%RH, the contact angle decreased almost linearly with time while the contact radius remained constant. The thesis interprets this behavior as evaporation on a high-energy surface that keeps the drop pinned.
Mid-range humidity held Teflon near 127°
On spin coated Teflon, the advancing contact angle was around 127° for temperatures between 50°C and 70°C at humidity levels between 53% and 65%RH. Within that range, temperature did not significantly change the measured advancing angle.
Near-saturation humidity lowered the Teflon angle
Comparing 53-65%RH with 94-100%RH, the average advancing contact-angle difference was 5.1°, regardless of temperature. "The thesis links this trend to increased effective surface energy of the flat Teflon coating with vapor deposition." The literature benchmark being reproduced (Weisensee et al.) reported approximately 9° over the same temperature range against the chamber's 5.1°. The thesis attributes the offset to "the nature of a prepared Teflon surface having high contact angle hysteresis" and notes "it is difficult to fabricate a surface with identical contact angles."
Figures & Visuals
What it shows
Shows the pendent droplet centered in the chamber for surface-tension testing, with the needle position and reported droplet volume of 39 µL.
What it shows
What it shows
Shows time-resolved sessile-drop images and the drop-angle decline at 27.5°C and 61%RH alongside literature values.
What it shows
Plots advancing contact angle against temperature for two humidity bands, making the humidity-driven offset easy to see.
Why It Matters
The thesis was motivated by interfacial phenomena involving temperature and humidity, and surface tension plus contact angle were the main measurements used to verify that the chamber could recreate literature-like droplet behavior under controlled conditions. In practice, those outputs connected the chamber design to actual droplet benchmarking on DI water.
Their value in the study was comparative rather than promotional: they showed agreement with literature for the glass and Teflon contact-angle benchmarks and for the 40°C surface-tension trend, while also exposing a lower-temperature surface-tension discrepancy that the authors singled out for further investigation.
Practical Takeaways
Benchmark with both tension and wetting
The thesis validated the chamber with pendent-drop surface tension and sessile-drop contact-angle measurements, so the performance check covered both liquid-air and liquid-solid behavior.
Treat humidity as a live surface variable
At 40°C, surface tension changed with relative humidity, and on flat Teflon the advancing angle shifted between mid-range and near-saturation humidity bands.
Use evaporative receding tests to confirm pinned behavior
On glass, the receding-angle benchmark captured the nearly linear angle decline with constant contact radius used as the literature comparison.
Recheck low-temperature water curves when results disagree
The 15°C surface-tension benchmark is where the authors flagged a discrepancy, making that region important for verification.
A smartphone workflow supported the benchmark set
The authors used the DropletLab© sessile and pendent apps with chamber-window imaging and LED backlighting for the surface-tension and contact-angle measurements reported here.