University of Twente researchers develop electronics-free soft robot for stomach diagnostics
Researchers at the University of Twente have developed SeroTab, a swallowable soft robotic minitablet that can sample stomach fluid and measure acidity without a battery, chip or onboard electronics. The work, published in Science Advances, was carried out with the University of Groningen, Fudan University and Hong Kong Baptist University. In an exclusive Q&A with MoveTheNeedle.news, the researchers described the system as a proof-of-concept for a broader generation of electronics-free soft robotic diagnostic capsules.
The research arrives at a time when healthcare systems are looking for less invasive diagnostic tools that can potentially reduce pressure on hospitals and improve patient comfort. Endoscopy remains a widely used method for examining the stomach and gastrointestinal tract, but it is invasive, uncomfortable for many patients and dependent on specialist infrastructure.
SeroTab does not replace the full capabilities of endoscopy. Instead, the project explores whether certain diagnostic tasks — such as measuring stomach acidity and collecting gastric fluid samples — can be performed using soft materials, magnetic guidance and ultrasound rather than onboard electronics.
A swallowable soft robot guided by magnets
Unlike most ingestible medical devices, SeroTab contains no internal electronics, batteries or cameras. Doctors guide the capsule through the stomach using a handheld external magnet placed against the patient’s skin. Magnetic particles embedded inside the robot respond to the magnetic field, allowing the device to bend slightly and glide along the stomach wall.
“The slight bend and how it moves are inspired by a penguin sliding on its belly,” said Venkat Kalpathy Venkiteswaran, corresponding author of the publication.
The robot’s sensing system relies on a hydrogel — a water-rich polymer material — that swells when exposed to stomach acid. Small markers embedded in the gel allow that swelling to be detected using a standard ultrasound scanner from outside the body. According to the published research, the device can measure acidity within the physiologically relevant pH range of 2 to 7.
SeroTab can also collect gastric fluid samples. A radio wave activates a miniature pump inside the capsule, transferring stomach fluid into a small internal chamber. The sample can then be analysed in a laboratory, including through metabolomic profiling, which studies molecules associated with biological processes and disease states.
The researchers say the procedure could eventually be completed in under twenty minutes in clinical settings.
Why remove the electronics?
Ingestible diagnostic devices typically rely on embedded electronics such as batteries, sensors, cameras and wireless transmitters. SeroTab takes a different approach by deliberately eliminating those components.
“We believe that an electronics-free approach has potential because it eliminates the need for batteries (with limits on usage time) and also makes it possible to make fully-soft devices, which are better for safety reasons,” the researchers told MoveTheNeedle.news.
That design philosophy reflects a broader challenge in soft robotics. Many soft medical systems still depend on rigid electronic components to power sensing and communication, creating trade-offs between flexibility, durability and patient safety.
SeroTab distributes those functions differently. Movement is controlled magnetically, sensing is read externally via ultrasound, and fluid sampling is activated wirelessly. The result is a fully soft ingestible system designed to reduce internal complexity.
The researchers also argue that simplifying procedures could help make some forms of diagnostics more accessible outside large hospitals.
“We would like to simplify medical procedures, so that diagnostics can be done in clinics rather than hospitals, making it more accessible for patients and reducing costs,” they said.
What SeroTab can — and cannot — do
The researchers position SeroTab primarily as a platform for early diagnostics and monitoring rather than as a direct replacement for endoscopy.
Traditional endoscopy allows doctors to visually inspect tissue, take biopsies and sometimes perform treatment during the same procedure. SeroTab does not currently provide those capabilities.
Instead, the device focuses on local chemical sensing and fluid collection inside the stomach without inserting a camera tube through the throat.
“Currently, measuring of biomarkers (pH, CO2, temperature etc.) in the stomach and intestines is done either using invasive endoscopy, or in many scenarios is not possible,” the researchers said. “SeroTab provides a non-invasive method for this, which will make these procedures painless, as well as improve diagnostics and monitoring.”
In reported animal-model experiments, the system detected pH changes after administration of omeprazole, a medication that reduces stomach acid production. The researchers observed pH changes from around 2 to around 6, demonstrating the device’s ability to measure chemically relevant changes inside the stomach.
The work nevertheless remains early-stage research. SeroTab has been tested in laboratory settings, ex vivo pig organs and live animal models, but not yet in humans. Further validation, safety testing and regulatory approval would still be required before clinical deployment.
International collaboration across robotics, materials science and diagnostics
The project combined expertise across robotics, materials science and biomedical diagnostics.
According to the researchers, the capsule, magnetic motion system and miniature pump were developed at the University of Twente and the University of Groningen. Researchers at Fudan University synthesised the pH-sensitive hydrogel, while Hong Kong Baptist University analysed and tested biological samples.
The work also reflects the growing role of the Netherlands in soft robotics and medical technology research. The University of Twente’s TechMed Centre has increasingly focused on robotics-assisted healthcare, minimally invasive diagnostics and advanced biomedical engineering.
Beyond stomach-acidity sensing
The researchers see SeroTab as a foundation for broader electronics-free diagnostic systems rather than a single-purpose device.
“SeroTab is indeed intended as a proof-of-concept for a broader platform for soft robotic capsules,” the researchers said. “While SeroTab can detect changes in pH in the stomach, we see future versions targeting more challenging applications, such as detecting diseases and providing targeted medicine in the intestines.”
Future versions could also measure temperature or detect internal bleeding, according to the University of Twente announcement. Those capabilities, however, remain future research directions rather than demonstrated clinical applications.
The broader significance of SeroTab lies in the engineering approach itself. Many medical devices continue to become more computationally complex, adding additional electronics, sensors, and wireless systems. The University of Twente-led team is testing whether some diagnostic functions can instead be achieved through softer materials, external control systems, and simplified device architectures.
For patients, that could eventually mean less invasive diagnostic procedures. For researchers in soft robotics, it demonstrates that useful sensing and sampling functions may be possible without embedding conventional electronics inside the body.
At this stage, SeroTab remains a carefully bounded research project rather than a clinical product. But it offers a glimpse into how future medical robotics may evolve: not only through more computing power but also through simpler, softer and potentially more accessible designs.
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