Contents
Case Study

Murdoch University had provisional approval for an optical tensiometer. After a software demo it chose the Dropometer, then learned to get contact angles from rough, absorbing soil.

Last Updated
October 18, 2026
Industry
Agricultural and Soil Science Research
Location
Perth, Western Australia
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Validated against KRÜSS DSA100E Published accuracy 0.35° 2 peer reviewed validation papers

A research group at Murdoch University's Centre for Sustainable Farming Systems needed water contact angle on treated and untreated soil. Standard sessile drop analysis struggled on it: uneven baselines, cluttered texture and drops that soak in quickly. On a February 2026 call, our engineering team showed that the Tilted Angle app, Extended detection and tight cropping returned angles on a soil image that had failed every point placement mode.

Abhimanyu Photo
Written by
Abhimanyu Bhandankar
Holds an MBA from Schulich School of Business and a BE in IT. He joined Droplet Lab in July 2019 and now leads sales and marketing.
CEO at Droplet Lab
Read More
Gurdeep-Saini-Photo
Technical Review by
Gurdeep Singh Saini
Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.
COO at Droplet Lab
Read More
Abhimanyu Photo
Written By

Abhimanyu Bhandankar

CEO at Droplet Lab

Holds an MBA from Schulich School of Business and a BE in IT. He joined Droplet Lab in July 2019 and now leads sales and marketing.

Gurdeep-Saini-Photo
Reviewed By

Gurdeep Singh Saini

COO at Droplet Lab

Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.

Primary outcome: a soil image that failed to calculate returned left and right angles

Soil images that would not calculate

Before calculation error
After 37° / 35° returned

On a test soil image, the app returned a calculation error under Smart, Extended and Manual point placement. The drop filled a small part of the frame, so contact points landed a few pixels off the true edge. After cropping the same image tightly and using the Tilted Angle app to bend the baseline to the soil surface, the analysis returned left and right contact angles of 37° and 35°. The fix was image handling and mode selection, not hardware.

1 kg portable kit

Sets up in about 2 minutes and leaves a route from lab tubes to pot trials, which the group wants for later work.

4 on one portable unit

Contact angle, surface tension, surface energy and sliding angle, with lifetime licences included.

2 researchers on one unit

Dr Sanchez-Palacios onboarded the instrument in October 2025, and postdoctoral fellow Samantha Viljoen now runs the soil measurements.

3 settings, not hardware

Tilted baseline, Extended detection, and tight cropping. The combination that made soil images calculable.

Executive Summary

Who

A research group at Murdoch University's Centre for Sustainable Farming Systems in Perth, Western Australia, led by Dr Tona Sanchez-Palacios, Murdoch-CSIRO Innovation Research Fellow. The group works on fluid fertilisers and on a biodegradable material sprayed onto soil to change how water behaves at the surface.

Problem

The group had no contact angle capability at all. Soil water repellency was the quantity that would decide whether a treatment worked, and it was not being measured. Once the instrument arrived, a second problem appeared: real soil is a hostile substrate for standard sessile drop analysis. Uneven surfaces gave no straight baseline, surface texture confused edge detection, and droplets penetrated fast enough to be missed at the phone's capture rate.

Solution

The Dropometer with all four measurements and the automatic dropper, delivered in October 2025. In February 2026 a troubleshooting call set out a soil approach: the Tilted Angle app for bent baselines, Extended detection for cluttered backgrounds, tight cropping before analysis, and a rule for choosing between Young-Laplace and Polynomial fits.

Time to Value

First contact 15 July 2025. Demo 22 July. Vendor approved 19 August and purchase order 25 August. Instrument in the lab 17 October after customs. Onboarding call 23 October. Feedback call 20 January 2026. Soil troubleshooting call 26 February 2026, Perth time.

Results

A soil image that returned calculation errors under every point placement mode returned left and right contact angles once cropped and analysed with a tilted baseline. The team now has rules for choosing a fit and a detection mode. The treated versus untreated soil comparison is in progress, and repeatability figures are not yet reported.

Highlights

37° / 35°

Left and right angles on a soil image that first returned a calculation error

4

Measurements in one portable kit: contact angle, surface tension, surface energy, sliding angle

2

Researchers using the instrument: a research fellow and a postdoctoral fellow

Quote teaser

"Switching to the tilted one, and being able to crop the photo, actually solves all the problems."

Murdoch University, at a glance

Research focus

Fluid fertilisers for agronomic purposes, and a biodegradable soil-applied treatment designed to change water behaviour at the soil surface

Products / applications

Biodegradable smart material sprayed onto soil to influence water behavior (supporting goals such as improved water-use efficiency, reduced irrigation needs, and yield resilience)

Measurement stage

R&D method development and formulation screening: measuring wettability on treated versus untreated soil

Users (roles/shifts)

A research fellow and a postdoctoral fellow, with PhD students to be trained on the workflow

Materials and surfaces tested

Fine sandy soils and coarse aggregated soils in tubes (~5 to 10 cm), soil columns (~50 cm), sprayed material deposited on paper, and leaf samples

Key constraints

Non-uniform surfaces with no straight baseline; rapid droplet penetration on repellent soils; sample heights up to 50 cm; portability and power for eventual field work

Real soil breaks the standard sessile drop workflow

Three separate problems, only one of which was about the instrument.

There was no measurement before this

There was no incumbent method to improve on. The group was not measuring contact angle at all. The soil project is roughly a year old, and the team saw early that it needed to quantify soil wettability to make any claim that a treatment works. The instrument was bought to close that gap before it became a bottleneck.

Why soil is a hard substrate

  • A non uniform soil surface gives sessile drop contact angle analysis no straight baseline to lock onto
  • Surface texture around the drop reads as edge candidates, so automatic detection picks the wrong contour
  • Drops on repellent soil are asymmetric, so left and right contact angles genuinely differ, sometimes by more than 5°
  • On less repellent soil the drop soaks in faster than the phone's 10 to 15 fps capture can reliably catch
  • Viewing angle matters: a dip in the surface on one side makes the apparent baseline sit lower on that side
  • Coarse aggregated soils cannot be flattened without destroying the property being measured

What was actually at stake

Water contact angle is the signal that decides whether a soil treatment has done anything. It is the same question behind soil amendment surface energy and water drop penetration testing, and a core measurement in our Farming and Agriscience guide. If that number is unreliable, formulation comparisons stall, and the case for moving from lab to pot trials to field trials cannot be made. The group had a March deadline and a team waiting to be trained.

What success would require

  • Angles that calculate reliably on rough, porous, absorbing surfaces
  • A procedure simple enough to teach to several team members quickly, the basis of reproducible contact angle measurement
  • Rules a user can follow without the underlying fitting mathematics
  • A path toward taller samples and, later, field conditions

The fix was image handling, not hardware

What Was Deployed

Delivered configuration (purchase order August 2025, in the lab October 2025): the Dropometer contact angle and surface tension kit with all four measurement apps (contact angle, surface tension, surface energy and sliding angle), the automatic dropper for controlled drop volume and flow rate, and a dedicated Pixel phone. A fabric sample holder for leaf samples was added to the quote after the demo. Lifetime software licences are included.
The Origin

A demo booked specifically to stress-test the software

Dr Sanchez-Palacios found Droplet Lab through the website on 15 July 2025 and configured a quote himself with the online builder, listing the use case as fluid fertilisers for agronomic purposes. He then asked for a demonstration with a clear purpose: to see whether the software could handle the sample types and protocols the lab intended to establish. He was not shopping without a budget. He already had provisional approval to purchase an optical tensiometer. In his words, the Dropometer looked good, but he wanted to check the software before committing. For labs weighing the same choice, our guide to the best contact angle goniometer for advanced research sets out the tradeoffs. The demo ran on 22 July. It changed the configuration rather than the decision: a fabric sample holder for leaf samples was added to the quote the same day. About five weeks of university vendor onboarding followed, with liability insurance, a modern slavery declaration and banking proof, before the purchase order arrived on 25 August. The instrument reached the lab on 17 October after customs clearance.
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Decision Rationale

Why not the instrument already provisionally approved

Three options, one of which already had provisional approval.

Option 1
Not disclosed

Buy the provisionally approved optical tensiometer

Provisional approval was already in hand. An established platform with established protocols, and a familiar route through procurement.

Not chosen. The group wanted to test the Dropometer software on its own sample types first, and a portable kit suited its plans for pot trials.
Option 2
$0

Continue without contact angle data

Keep assessing soil treatments on downstream proxies and defer wettability measurement until later in the project.

The group had already concluded this was untenable. Contact angle was the quantity the whole comparison rested on.
Chosen
US$4,990 list

The Dropometer, all four measurements

Contact angle, surface tension, surface energy and sliding angle in one portable kit, with lifetime licences and an automatic dropper for repeatable drop volume.

Chosen after a demo built around the group's own questions about the software.
The decision was made on software. Dr Sanchez-Palacios had approval for a conventional instrument and asked for a demo to test whether the software could handle his sample types before committing. The cost of the choice showed up later: soil is a difficult substrate, and about four months passed between delivery and a working approach on a test image. Soil is also not the surface ISO 27448 was written for; that standard covers water contact angle on photocatalytic surfaces, and the Dropometer supports the same sessile drop principle. The February 2026 call is the part of the offer a specification sheet does not capture.

Next Step

Measuring on a surface that will not cooperate?

Soil, powders, porous membranes and textured coatings all break the same assumption that standard sessile drop analysis makes. Send us a sample or an image that will not calculate, and we will run it and tell you what is going wrong. That is how the Murdoch soil work moved forward: one image, emailed during the call and analysed while the team watched.

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Before vs After

Metric Before After
Baseline handling Contact Angle app only, straight baseline. Uneven soil never gave the software a clean baseline to lock onto. Tilted Angle app. The baseline bends to follow the actual soil surface.
Image framing Full frame capture. The drop filled a small pixel area, so contact points landed a few pixels inside or outside the true edge. Tight crop around the drop before analysis, using the framing box on the capture screen.
Detection mode Smart mode against cluttered soil texture. Repeated calculation errors. Extended mode for cluttered backgrounds. Smart also works once the image is cropped well.
Algorithm choice No clear rule for Young-Laplace versus Polynomial. Polynomial for asymmetric drops and whenever the needle sits inside the drop. Young-Laplace for symmetric drops clear of the needle.
Result on the test image Calculation error under Smart, Extended and Manual placement. Left and right contact angles returned (37° and 35°).
Transferability Know how held by one user. Decision rules from the call that other team members can follow.

Rollout timeline

Timeline (high level)

15 to 22 July 2025: Evaluation

  • Website enquiry and self-configured quote; use case recorded as fluid fertilisers for agronomic purposes
  • Demo requested explicitly to assess software capability against intended sample types
  • Demo delivered 22 July; fabric sample holder for leaf samples added to the configuration

22 July to 25 August 2025: Procurement

  • University vendor onboarding: liability insurance certificate, modern slavery declaration, banking proof
  • Vendor approved 19 August; purchase order issued 25 August

September to 17 October 2025: Delivery

  • Assembly and shipment from Toronto; customs clearance in Canada and Australia
  • Instrument reached the lab 17 October; Dr Alidad Amirfazli's demonstration video shared ahead of onboarding

23 October 2025: Onboarding

  • Live onboarding session covering project setup, density entry, manual and automatic injection, Bluetooth pairing, sessile stage levelling, focus, lighting, and baseline placement
  • Needle selection guidance: thinnest needle the liquid allows for contact angle, surface energy, and sliding angle; largest needle for surface tension
  • Calibration path established: measure needle outside diameter directly rather than relying on supplier figures

20 January to 26 February 2026: Soil troubleshooting

  • 20 January feedback call: unclear images on uneven soil, dropper consistency and capture rate raised
  • 26 February call with our engineer: Tilted Angle app, Extended detection and tight cropping returned angles on a test image
  • Young-Laplace versus Polynomial decision rule explained for the team

What has been demonstrated, and what has not

Test method

Sessile drop water contact angle on treated and untreated soil. Tilted Angle workflow with a bent baseline set slightly above the contact points. Polynomial fitting for asymmetric droplets, which reports left and right angles independently and tolerates the needle remaining inside the droplet. Young-Laplace reserved for symmetric droplets clear of the needle, where it also returns droplet volume.

Sample size and operators

Not yet reported. Two researchers have used the instrument so far, and wider training is planned.

Repeatability / reproducibility

Not yet reported. The group is running its first standardised batch.

Notes / assumptions

Soil roughness and porosity produce genuinely asymmetric droplets, so a difference between left and right angles is a property of the sample rather than an analysis artefact. Contact angles on rapidly penetrating soils are time-dependent and capture-rate limited at 10 to 15 fps; a higher-speed path exists if droplet dynamics become the object of study rather than a nuisance.

Outcomes to date

Measured Outcomes

37° / 35°

Angles returned on a test image

A representative soil image that returned calculation errors under Smart, Extended, and Manual point placement returned left and right contact angles once cropped and analysed with a bent baseline. Same image, same instrument, different handling.

3

Root causes identified

Baseline geometry, pixel-scale contact point placement on an uncropped frame, and detection mode against cluttered texture. All three were addressable in software settings and image handling.

2

Researchers on one unit

Dr Sanchez-Palacios set up and onboarded the instrument in October 2025. By December 2025, postdoctoral fellow Samantha Viljoen was running the soil measurements, and PhD students are next.

Operational Outcomes

Procedure, not hardware

The blocking issue was procedure, not equipment. Cropping tightly around the droplet and bending the baseline to the surface converted failures into measurements without any hardware change.

Rules a team can share

The group has decision rules for when to use Polynomial or Young-Laplace and when to switch to Extended detection, rather than one person's intuition. That is what a multi user rollout needs.

Field needs defined

Field deployment constraints are now specific and actionable: stand height for 50 cm columns, backlight battery life at working brightness, and phone-holder clearance. All three are in Droplet Lab's hardware feedback loop from this deployment.

What the team said

"Switching to the tilted one, and then also just being able to crop the photo, actually solves all the problems. I think that has actually answered all the questions we have, because now we know how to set it up." At the end of the onboarding call on 23 October 2025, after the first measurements on the new instrument: "We're going to start running some samples, but it looks good ... it looks pretty good."
Samantha Viljoen - Postdoctoral Fellow

An open feedback loop

Delivered

Dropometer with all four measurement apps and the automatic dropper, delivered to Perth in October 2025
Onboarding session covering assembly, injection control, Bluetooth pairing, and baseline placement
Soil troubleshooting call: tilted baseline, Extended detection, tight cropping and fit selection rules
Demonstration video by Dr Alidad Amirfazli, Co-founder and Scientific Advisor, shared before onboarding

In Pilot

Multi-user training across the wider research team ahead of the measurement campaign
USB-C dongle for direct mouse control of the phone, for finer contact point placement
Needle outside diameter measured by micrometer, enabling Young-Laplace work alongside Polynomial
Backlight operation at 1 to 2 percent brightness to extend battery life toward field use

Planned

Freestanding, vertically adjustable phone stand for soil columns up to 50 cm
Phone holder redesign to avoid contact with the handset volume buttons during capture
Glossary entries for Young-Laplace and Polynomial fitting in the Surface Science Hub
Extension of the workflow from tubes to columns, and from lab to pot and field trials

Frequently asked questions

Can you measure water contact angle on soil?

Yes, with care. Soil gives no straight baseline, its texture confuses edge detection, and drops can soak in quickly. On a February 2026 call, the Tilted Angle app, Extended detection and tight cropping returned left and right angles of 37° and 35° on a soil image that had first returned a calculation error.

Which fit should I use on rough or asymmetric drops?

The Polynomial fit measures left and right angles independently and works with the needle still in the drop, which suits asymmetric drops on soil. The Young Laplace fit assumes an axisymmetric drop and averages both sides.

Why did the group choose the Dropometer over an approved optical tensiometer?

The group already had provisional approval for an optical tensiometer, but wanted to test the Dropometer software on its own sample types first. After a demo on 22 July 2025 it chose the Dropometer, and a portable kit suited its plans for pot and field trials.

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Next Step

Measuring on a surface that will not cooperate?

Soil, powders, porous membranes and textured coatings all break the same assumption that standard sessile drop analysis makes. Send us a sample or an image that will not calculate, and we will run it and tell you what is going wrong. That is how the Murdoch soil work moved forward: one image, emailed during the call and analysed while the team watched.

Request a quote Book a 15 minute demo