Dropometer
US$4,990 base kit, checked 23 October 2026
Contact angle goniometer comparison
Dropometer vs Biolin Scientific Attension Theta
Biolin Scientific's Attension Theta optical tensiometers come in three models: Theta Lite, Theta Flex and Theta Flow. They measure contact angles, surface free energy and surface and interfacial tension, with modules for roughness, interfacial rheology, high pressure and automation. This page compares the range with the Dropometer on price, accuracy, methods and where each can measure.
VS
Attension Theta Lite, Flex and Flow
Quote only. A US seller's cost guide puts entry optical tensiometers at US$5,000 to US$15,000, mid range at US$15,000 to US$40,000 and high end at US$40,000 to over US$100,000; checked 23 October 2026
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
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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
The short answer
Buy an Attension Theta if you need roughness corrected contact angle, interfacial rheology, high pressure or temperature chambers, high speed video or surface tension above 75 mN/m. Buy the Dropometer (US$4,990) for contact angle, pendant drop surface tension and surface energy at room temperature, with accuracy validated against a KRÜSS DSA100E.
When an Attension Theta is the better choice
- Roughness corrected contact angle. The optional 3D Topography Module measures surface roughness and corrects the angle.
- More methods. Captive bubble and meniscus (fibre) contact angle on every model; pulsating drop interfacial rheology on the Flex and Flow.
- Wider ranges. 0° to 180° at ±0.1°, and surface and interfacial tension from 0.01 to 2,000 mN/m.
- Higher level of automation. Automated dispensers and, on the Theta Flow, an XYZ stage and software autofocus.
- Fast optics. Up to 2,068 fps on the Lite, 3,009 on the Flex and 3,422 on the Flow.
When the Dropometer is the better choice
- Price. US$4,990 with a published price; Theta pricing is by quote.
- Validated accuracy. 0.35° contact angle accuracy measured against a KRÜSS DSA100E in peer reviewed papers.
- Portable. Battery power for up to 8 hours and offline analysis on the included phone; the lightest Theta, the Lite, is a 5 kg mains instrument.
- The everyday measurements in one app. Static and dynamic contact angle, pendant drop surface tension up to 75 mN/m and surface free energy.
- Support. 5 year warranty and 5 years of software updates.
When not to buy a Dropometer
- You need roughness corrected contact angle: Biolin's 3D Topography Module does this on the Theta Flex and Flow; the Dropometer does not.
- You study interfacial rheology, or measure at high pressure (up to 400 bar and 200 °C) or controlled temperature.
- You need 0.1° stated accuracy, contact angles below 10° or above 175°, or surface tension above 75 mN/m.
- You need high speed video: the Theta Flex camera reaches 3,009 fps.
- You need audit trails or electronic signatures, which the Dropometer does not support.
Executive summary
Both measure wetting from drop shape. The Attension Theta range is a premium contact angle meter platform: three frames, a choice of automation level and a long list of modules, run from OneAttension software on a PC. The Dropometer is one portable kit for the measurements most labs run every day: static and dynamic contact angle, pendant drop surface tension and surface free energy, at room temperature, for US$4,990.
Where they overlap
Static and dynamic contact angle measurements on a sessile drop.
Surface free energy from the contact angles of several test liquids.
Surface and interfacial tension by the pendant drop method with a Young–Laplace fit.
Where they differ and why it matters
Price
Biolin sells the Theta by quote. The Dropometer is US$4,990, with optional tilt stage (US$700) and auto dropper (US$2,000).
Methods and modules
The Theta adds captive bubble, meniscus, roughness correction, interfacial rheology and high pressure. The Dropometer covers sessile, tilted and pendant drop methods.
Accuracy and range
Biolin states ±0.1° over 0° to 180°. The Dropometer's 0.35°, measured against a KRÜSS DSA100E, covers 10° to 175°.
Where you can measure
Every Theta runs on mains power with a PC: 5 kg (Lite) to 29 kg (Flow). The Dropometer runs on battery and goes to the sample.
A deeper look at the criteria that decide it
Which Attension Theta models we compared
- Theta Lite: the compact model, 5 kg, 1.3 MP camera at up to 2,068 fps, manual focus, Auto 1 and Auto 2 dispenser options. No roughness, rheology or high pressure modules.
- Theta Flex: the modular research and quality control model, 26 kg, 2.3 MP at up to 3,009 fps; takes the 3D Topography Module, pulsating drop and high pressure chamber.
- Theta Flow: the premium model, 29 kg, 5 MP at up to 3,422 fps, software autofocus, touch display and automation up to an XYZ stage (Auto 5).
- Theta Wafer: a separate premium model for fully automated contact angle measurements on silicon wafers. High pressure and pulsating drop options are built on the Flex or Flow. Brochure.
Roughness and the angle you read
On a rough surface the contact angle you measure is not the angle on a flat surface of the same chemistry. Biolin's 3D Topography Module measures the surface roughness under the drop and gives a roughness corrected contact angle, which matters for superhydrophobic and superhydrophilic coatings. The Dropometer measures advancing and receding angles, whose gap, the contact angle hysteresis, shows that roughness is present, but it does not correct for it.
Level of automation
Biolin offers several automation levels: automated dispensers on every model, and on the Theta Flow an automated XYZ stage and autofocus; the Theta Wafer automates measurements on silicon wafers. For hands off series on many samples, that is a real advantage. The Dropometer automates edge and baseline detection and, with the optional auto dropper, drop dosing; positioning stays manual. Our high throughput QC guide covers automated work.
What the price buys
A Theta's price pays for the frame, the camera speed and the modules you choose. If your research needs interfacial rheology, pressure or roughness correction, nothing cheaper replaces them. If your work is wettability measurements, surface energy and surface tension at room temperature, the Dropometer covers it for US$4,990 and leaves budget for a second site.
Specification and capability matrix
| Criterion | Dropometer | Theta Lite | Theta Flex | Theta Flow |
|---|---|---|---|---|
| Price (checked 23 October 2026) | US$4,990 base kit (phone and lifetime licence included) | Quote only | Quote only | Quote only |
| Contact angle | 10° to 175°; 0.35° accuracy vs a KRÜSS DSA100E (peer reviewed); 0.01° resolution | 0° to 180°, ±0.1° | 0° to 180°, ±0.1° | 0° to 180°, ±0.1° |
| Advancing and receding angles | Advancing and receding in the app | Yes | Yes | Yes |
| Sliding or roll off angle | Optional tilt stage, US$700 (0° to 60°); auto tilt US$1,500 | Not listed | Tilting cradle or stage (0° to 90°) | Tilting cradle or stage (0° to 90°) |
| Surface and interfacial tension | Pendant drop, up to 75 mN/m; 0.01 mN/m resolution | 0.01 to 2,000 mN/m | 0.01 to 2,000 mN/m | 0.01 to 2,000 mN/m |
| Surface free energy | Equation of State, Fowkes, van Oss Chaudhury Good in the app; OWRK in our free calculator | Yes | Yes | Yes |
| Captive bubble and meniscus | No | Yes | Yes | Yes |
| Roughness corrected contact angle | No | No | 3D Topography Module | 3D Topography Module |
| Interfacial rheology | No | No | Pulsating drop module | Pulsating drop module |
| Camera | Pixel 7a phone camera, 10 fps, 4x zoom, manual focus; high power LED backlight | 1.3 MP, up to 2,068 fps | 2.3 MP, up to 3,009 fps | 5 MP, up to 3,422 fps |
| Temperature and pressure | Operates 10 to 45 °C as standard; temperature and humidity chamber available as a built to order upgrade (ask for range and lead time) | Not listed | Chambers to 250 °C; high pressure to 400 bar and 200 °C | Chambers to 250 °C; high pressure to 400 bar and 200 °C |
| Automation | Optional auto dropper and auto tilt | Auto 1 and 2 dispensers | Auto 1, 2, 4 and Plus | Auto 1 to 5 (XYZ stage), autofocus |
| Weight and power | 5 V, battery up to 8 h; 1 kg; sets up in about 2 minutes | 5 kg; mains 100 to 240 V | 26 kg; mains | 29 kg; mains |
| Software | Android app on the included phone, or your own iPhone (iOS 15 or later); analysis offline; lifetime licence | OneAttension on a PC | OneAttension on a PC | OneAttension on a PC |
| Warranty | 5 years (phone and syringe excluded as consumables), plus 5 years of software updates | Not published | Not published | Not published |
Checked 23 October 2026. Theta figures come from Biolin Scientific's 2024 Attension Theta range and modules brochures. Biolin does not publish prices; the price bands come from the cost guide of Nanoscience Instruments, which sells Attension instruments in the US (updated July 2025). Dropometer figures come from the Dropometer specification.
How we built this comparison
We compared Biolin Scientific's published specifications for the Theta Lite, Flex and Flow with the Dropometer's specification and its peer reviewed validation against a KRÜSS DSA100E. We have not measured a Theta ourselves. Where Biolin does not publish a figure, such as a price or warranty, the page says so.
Disclosure: Droplet Lab makes the Dropometer, so read this page knowing that. Every competitor figure links to the maker's own page or datasheet, and where a figure is not published we say so. The verdict flips to a Theta as soon as roughness correction, interfacial rheology, high pressure, temperature control or tension above 75 mN/m is a requirement.
Expert perspective
Biolin's 3D Topography Module exists because roughness changes the contact angle you read. Dr. Alidad Amirfazli makes the related point about hysteresis: the gap between advancing and receding angles is where roughness shows up.
Where roughness shows up
"The gap between the advancing and receding angle, the hysteresis, is where a surface reveals its roughness, its heterogeneity, and whether something is reacting."
What this means here: if roughness drives your results, measure hysteresis on any instrument, and choose a Theta with the 3D Topography Module if you need the roughness corrected value itself.
Recommendations by scenario
Roughness corrected angles, interfacial rheology or high pressure
Pick: Attension Theta Flex or Flow with the module you need. See the advanced research guide.
Automated series or wafer handling
Pick: Theta Flow for automated series, Theta Wafer for wafers. See the regulated high throughput QC guide.
Contact angle, surface tension and surface energy at room temperature
Pick: Dropometer, US$4,990. See the under US$5,000 guide.
Measurements on the production floor or at a customer site
Pick: Dropometer. It runs on battery and analyses offline. See the field and on site guide.
Bottom line
An Attension Theta is the right buy for a lab that needs the modules: roughness correction, interfacial rheology, pressure and temperature chambers, high speed video or wafer measurements on the Theta Wafer. The Dropometer is the right buy when the work is contact angle, surface tension and surface energy at room temperature, in more than one place or on a tight budget. Book a 15 minute demo to see the measurements on your own samples.
Frequently asked questions
What is the difference between the Theta Lite, Theta Flex and Theta Flow?
The Lite is the compact 5 kg model with a 1.3 MP camera and fewer options. The Flex is the modular model that takes the 3D Topography, pulsating drop and high pressure modules. The Flow is the premium model with a 5 MP camera, autofocus and full automation.
How much does a Biolin Attension Theta cost?
Biolin Scientific does not publish prices. Nanoscience Instruments, which sells Attension instruments in the US, puts entry optical tensiometers at US$5,000 to US$15,000, mid range at US$15,000 to US$40,000 and high end at US$40,000 to over US$100,000 in its cost guide, updated July 2025.
Can the Dropometer measure roughness corrected contact angle?
No. It measures static, advancing and receding angles, and the hysteresis between them signals roughness, but it has no topography module to correct for it.
Is an Attension Theta more accurate than the Dropometer?
Biolin states ±0.1° over 0° to 180°; the Dropometer's accuracy is 0.35° over 10° to 175°, measured against a KRÜSS DSA100E in peer reviewed studies.
Can the Dropometer replace an Attension Theta?
For contact angle, pendant drop surface tension up to 75 mN/m and surface free energy at room temperature, yes. For roughness correction, interfacial rheology, high pressure, temperature control or automated series, no.
Other instrument comparisons
How the Dropometer compares with other contact angle goniometers and surface screening tools.
Dropometer vs Ossila Contact Angle Goniometer
Entry benchtop, about US$3,000
DIY ImageJ vs Dropometer
Free software plus a rig you build
Dropometer vs KRÜSS DSA100 and DSA25
Premium benchtop, quote only
Dropometer vs DataPhysics OCA series
Premium benchtop, quote only
Dropometer vs ramé-hart goniometers
Benchtop range with published prices
Dropometer vs Brighton Science Surface Analyst
Handheld water contact angle for production
Dropometer vs dyne pens and test inks
Pass or fail surface energy screening
All contact angle goniometer buying guides
Best instrument by budget and use case
Validated measurement approach
Where the Dropometer's accuracy figure comes from.
Benchmarked against a KRÜSS DSA100E
Dropometer contact angle and pendant drop surface tension were compared with a KRÜSS DSA100E in two peer reviewed papers: Review of Scientific Instruments (2018) and Colloids and Surfaces A (2017).
Used in 52 customer publications
Customers have cited the Dropometer in 52 peer reviewed papers, theses and conference papers, listed with links.
References
1.
Biolin Scientific: Attension Theta range brochure (2024)
Theta Lite, Flex and Flow specifications, checked 23 October 2026.
2.
Biolin Scientific: Attension Theta Flex and Flow modules and accessories (2024)
3D Topography, pulsating drop, high pressure, tilting and temperature options.
3.
Biolin Scientific: Attension optical tensiometers
Manufacturer product range page.
4.
Nanoscience Instruments: How much does a contact angle meter cost?
Distributor cost guide, updated July 2025; source of the price bands.
5.
Chen, Muros-Cobos and Amirfazli (2018). Contact angle measurement with a smartphone. Review of Scientific Instruments 89, 035117
Peer reviewed validation of the Dropometer's contact angle method against a KRÜSS DSA100E.
6.
Droplet Lab: Dropometer technical specification
Dropometer price, ranges, accuracy, add-ons and export formats, checked 23 October 2026.