KAIST and Seoul National University Bundang Hospital researchers built a flexible patch that uses a vitamin C and baking soda reaction to push medication into the eye, aimed at astronauts and people with hand tremors.
Putting in eyedrops is a small act that depends on something most people never think about: gravity. Tilt your head back, squeeze the bottle and the drop falls into place. In orbit, where everything floats, that simple routine becomes surprisingly difficult.
Researchers in South Korea have developed a way around the problem. A team from the Korea Advanced Institute of Science and Technology (KAIST) and Seoul National University Bundang Hospital has created a flexible, wearable patch that delivers eyedrops using gas pressure instead of gravity. The work was published in Sensors and Actuators B: Chemical.
“The flexible eyedrop patch developed in this study is a wearable platform that can deliver medication without complex additional equipment, and we expect it to expand to space medicine and other settings,” said Ki-Hun Jeong, a professor in KAIST’s Department of Bio and Brain Engineering who led the KAIST team.
Eye trouble in orbit
Eye problems are a well-documented concern in spaceflight. Many astronauts on long missions develop changes in their eyes, including swelling of the optic nerve and flattening of the back of the eyeball, a condition NASA calls spaceflight-associated neuro-ocular syndrome. Dry, irritated eyes are also common in the dry, recycled air of spacecraft, and floating dust and debris can get into the eyes.
Treating these problems can require eyedrops, but liquids behave strangely in microgravity. Without gravity to pull a drop downward, liquid tends to cling to surfaces and form floating blobs. Getting a precise dose into the eye becomes a matter of guesswork.
Astronauts have long improvised workarounds for everyday tasks in weightlessness. Drinking water comes from pouches with straws, food is packaged to prevent crumbs from floating away, and even washing hair requires special no-rinse shampoo. Medical care is no exception, and space agencies have been studying how to adapt treatments for future missions that will take crews far beyond quick reach of Earth.
Kitchen chemistry as a pump
The new patch solves the problem with a reaction familiar from science fairs. Inside the device, a small chamber holds vitamin C and baking soda. When the two come into contact with water, they react and release carbon dioxide gas.
That gas becomes the driving force. The patch combines a chamber that generates gas pressure with tiny channels that carry the liquid medication. When a user wearing the patch presses on an actuation area, the reaction starts, the gas pressure builds and the eyedrop is pushed through the channel toward the eye.
A filter sits between the reaction chamber and the chamber holding the medication. It lets gas pass through but blocks liquid, so the reacting chemicals never mix with the drug. The device needs no pump and no electrical power.
The first author of the study is Jaehun Jeon, a doctoral student in KAIST’s Department of Bio and Brain Engineering. Se Joon Woo, a professor at Seoul National University Bundang Hospital, led the hospital team.
Testing on Earth
Because the patch does not depend on gravity, its performance should not change with orientation. The researchers tested that by changing the direction of gravity relative to the device and found that it released drops consistently regardless of how it was positioned.
In an on-body test with human participants, the patch delivered medication at a level similar to that of conventional eyedrops.
Those tests were carried out on Earth. The researchers note that the device’s performance will still need to be verified in actual space conditions, which can only be approximated on the ground.
Help on the ground too
The team sees uses well beyond spaceflight. Many people struggle to aim an eyedrop bottle accurately, and the problem is particularly acute for people with hand tremors, such as patients with Parkinson’s disease. A patch that delivers a measured dose with a simple press could make treatment easier and more reliable.
Missed or misdirected drops are a real concern in eye care. For conditions such as glaucoma, in which eyedrops lower pressure inside the eye to protect the optic nerve, patients often need to use drops every day for years. Studies have found that many patients have difficulty administering them correctly, wasting medication or failing to get a full dose.
Microfluidics for medicine
The patch is an example of microfluidics, the engineering of devices that move tiny volumes of liquid through channels often narrower than a human hair. Microfluidic technology already underpins some rapid diagnostic tests and lab-on-a-chip devices, and researchers are increasingly adapting it for wearable systems that monitor health or deliver drugs.
Using a chemical reaction rather than electronics to drive the fluid is a key part of the design. It keeps the device simple, light and independent of batteries, all advantages for a spacecraft, where every gram and every power source counts.
Questions remain about how the patch would work in practice. The study does not describe how long it can be worn, how many doses it can hold or how it might be refilled or replaced. Those details will matter for long missions, such as future trips to the Moon or Mars, where crews will need to manage their own medical care far from Earth.
The work was supported by the Korean ARPA-H Project through the Korea Health Industry Development Institute, the National Research Foundation of Korea and the Technology Innovation Program. For now, it offers a small but practical solution to one of the many everyday tasks that become complicated once gravity is taken away.
Notes
- “Wearable self-instillation microfluidic eyedrop patch for space medicine.” Sensors and Actuators B: Chemical, 7 October 2026. DOI: 10.1016/j.snb.2026.140885.
- Korea Advanced Institute of Science and Technology (KAIST). “KAIST develops gravity-independent wearable eyedrop patch for use in space.” EurekAlert!, 20 October 2026. https://www.eurekalert.org/news-releases/1148441.
NASA