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For accuracy purpose, we are restricted to using specific phone models as we need access to raw images for best utilisation of our image processing algorithms. If you have access to a Motorola Stylus phone or an iPhone we will simply give you the rest of the setup reducing the price further.


We will ask you return the damaged component and provide you with a replacement at no cost.

Yes. You only need to purchase the updated phone model. We will provide compatible apps for the new phone model for free.

Yes. We offer free software updates for your device lifetime (4 Years)

Yes, with the exclusion of consumables (i.e. syringe, needle, batteries).

That’s up to the device manufacturer (Motorola). It’s currently 1-Year on the phone model included in package.

“The duration of the capture” means the total duration of the capture time. For example, if you want to take one image every 10s, and in total you want to take 60 images, what you need to set is “image to capture:60”, “duration of capture: 600s”.

The density different is the density of your sample liquid when you measure the surface tension of a liquid or contact angle between a liquid drop and a solid surface (under air). For example, when you conduct the measurement between water and air.
When you measure the interfacial tension between two immiscible liquids, the density difference is the density difference between these two liquids. When you measure the contact angle between a liquid drop and solid surface (under another liquid), the density difference is also the density difference between these two liquids.

1. For the surface tension measurement, you always need to correctly input the value.

2. For the contact angle measurement, you can leave it empty if you use polynomial method. And you to need to correctly input the value if you want to use the Yonge-Laplace method.

3. For measuring the titling angle, you don’t need to input the value.

4. For the energy: you can leave it empty if you use polynomial method.

The image calibrate is the diameter of the needle you used to generate a liquid drop for measurement. The gravity is the gravity acceleration. These two parameters need to be correctly input for the surface tension measurement. For the contact angle and solid surface energy, these two parameters are needed only when you want to use Yonge-Laplace method.

For any measurement, always try to use the minimal focus distance (i.e. Drag the focus bar to the top as shown in the following picture) for all the measurement.

Neumann Method: This method involves use of only One Liquid.

Fawkes Method: This method involves use of Two Liquids (1 purely Dispersive liquid and 1 polar liquid).

Oss & Good Method: This method involves use of Three Liquids (1 Dispersive liquid, 1 Acid, 1 Base).


The tilting stage has a raised end to hold the sample. You can also use a clamp to hold sample.

For the best results for the pendent drop methods comes from when the droplet is at the cusp of detaching from the capillary. At this point, the droplet is significantly “deformed”; taking a raindrop like shape.
This is because the surface tension of the droplet is trying to resist the force of gravity stretching the droplet. Thus, when the droplet is significantly deformed, surface tension is pushed to its limits. measuring the surface tension here will give the best results.

These three methods are the most widely used methods to calculate the solid surface energy. Any of them can calculate the solid surface energy for you. However, the literature suggests that depending on the type of surface you want to do the measurement for, one/ two of these methods may perform better than others. So, we suggest that you first check what method is most widely used for your sample in the literature and select the same when you do your measurement.

We suggest using the flow rate of 1-2 ul/s. One rotation of the syringe plunger included in package means 10ul. You can calculate the rotating speed based on this value.

You need to do calibration if you are using Yonge-Laplace method for contact angle measurement. You do not need to do the calibration for the Polynomial fitting method.

In the Yonge-Laplace method, the drop profile is fixed with the best possible solution of Yonge-Laplace equation. This method gives the best results when you are working with an axisymmetric drop. The Polynomial fitting methods fit part of the detected profile with center polynomials. This method can work with all types of drops.

The volume for the surface tension measurement is dependent on the properties of the sample liquid and the needle which is used to generate the drop. The range for the volume is typically between 15ul-30ul. The criterion deciding the volume is whether the liquid drop is well deformed (not a spherical shape). The best approach for generating a well deformed drop is:

1. Slowly increase the volume and remember the shape of the drop just before the drop detaches from the needle.
2. Generate a second drop with the similar shape as the last one before detaching.

For surface tension measurement (interfacial tension between liquid and air), we suggest using a flat head needle with a diameter larger than 1.75mm.

Yes, we provide a bubble level for free as part of the package.

1. Get into the drop picture and drag the orange line into the middle of the needle.

2. Drag the small bar to the needle. And click the three dots in the right top of the screen.

3. Click calibrate.

When you generate a drop from bottom, please put the needle (using the syringe holder) into your first image (as shown in the picture below). And do calibration based on this needle in your measurement.

1. Make sure you put the calibration bar not too close either to the up end of the image or the drop.

2. Try to make the needle to be vertical in the image.

3. Use a needle with the size larger than 1.65mm.

4. The calibration number you get should be smaller than 7um/px.


If you are using the Young-Laplace method, you need to input the needle diameter to calibrate the needle to pixels. This calibration is not necessary for Polynomial method. We also provide a bubble level to level the stage. No other calibration is needed.

We can reach as fast as 10 frame per second.

Yes, we can. The picture below shows how our automatic version Dropometer measures the interfacial tension between two immiscible liquids. We can also measure the contact angle of a liquid under another immiscible liquid.

Our system is capable of doing this work. We can also change the sample size and rate if needed. Doing this work needs a cell to hold the sample and liquid and inject the gas (e.g. CO2). However, we need you to set up the sample cell. If you want us to do the cell, then we need to have a separate order for them.

Yes. Our software has a multi-capture feature which allows you to do those measurements.

The precision is 0.01ul with the 250ul syringe from Hamilton. We have maintained the syringe onto vertical transform stage which allows you to retract the syringe tip smoothly.

Yes, the syringe does move in the Z-direction.

We have a one-size, syringe holder currently for the size of Hamilton syringe we ship in the package. If you need it to be wider, just let us know what size you need and we can custom design one for you

For the titling measurement, we suggest using a sample with thickness less than 4mm.

Any solvents can be used, drop range can be between 10ul to 75ul.

We provide 4 different apps for different measurements. Depending on the version of the Dropometer you ordered, you can find one or more of the apps installed in the smart phone.

Pendant App: Measure the surface tension of liquids and interfacial tension between immiscible fluids.

Sessile App: Measure the contact angle (including static, advancing and receding contact angle) between a liquid drop and solid surface.

Tilting App: Measure the sliding angle of a drop with a solid surface.

Energy App: Measure the surface free energy of a solid surface.

  • Yes. – CSA, UL, etc.

Yes. Please go to our Scientific Validation page to find out more information.

Package content PDF.

We use Hamilton Syringes for both the versions



In the standard version, the drops will be generated manually. We include the below syringe from Hamilton in the package.

In automatic, you can generate a liquid drop with a set volume and the flow rate. Additionally, for the sliding angle measurement, the tilting of the stage will be manual. In automatic, you can choose the tilting rate and angle. Everything else apart from these 2 components including the measurement process is the same.

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