Applying eyedrops is difficult in space, where there is almost no gravity. A KAIST research team has developed a wearable patch that delivers eyedrops to the eye without relying on gravity. The research team was led by Professor Ki-Hun Jeong from the Department of Bio and Brain Engineering, in collaboration with a research team led by Professor Se Joon Woo from Seoul National University Bundang Hospital. The paper is published in the journal Sensors and Actuators B: Chemical.
During long-duration space exploration, technologies that allow astronauts to manage their health without direct help from medical staff are essential. In particular, microgravity causes body fluids to shift toward the head, which can change the structure of the eyes and visual function. However, the standard method of applying eyedrops on Earth depends on drops falling by gravity, so it cannot be used in space without modification.
Gas pressure replaces gravity
The research team combined microchannels that carry liquid with a chemical reaction chamber that generates pressure, all in a single flexible patch. When the user wears the patch and presses the actuation area, the pressure of the gas generated inside delivers the eyedrop to the eye.
The patch works through a reaction between vitamin C and baking soda. When ascorbic acid (vitamin C) and sodium bicarbonate (the main component of baking soda) come into contact with water, carbon dioxide gas is produced. The resulting pressure pushes the eyedrop along the microchannel. Instead of relying on gravity to move the eyedrop, the patch uses pressure generated inside it.
A filter placed between the reaction chamber and the eyedrop chamber allows gas to pass but blocks liquid. This keeps the reactants and the eyedrop separate while still transmitting the gas pressure. Because the patch needs no external pump or electrical drive, it is expected to be suitable for settings where equipment is limited.
Earth tests show consistent delivery
The research team confirmed that the patch released eyedrops consistently even when the direction of gravity was changed. In an on-body evaluation with human participants, the patch also delivered the drug at a level similar to that of the conventional eyedrop method. These results demonstrate the potential of an eyedrop delivery method that does not depend on the direction of gravity.
The study presents a personal drug delivery technology that allows people to apply eyedrops by themselves in space. Note, however, that these results come from experiments with different gravity directions and an on-body evaluation conducted on Earth. Use in an actual space environment still requires further verification.
Potential help for patients with tremors
The technology could also be used on Earth. It is expected to help people who have difficulty aiming an eyedrop container at the eye because of hand tremors or other physical limitations, such as patients with Parkinson’s disease.
“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 professor Jeong.
More information
Jaehun Jeon et al., Wearable self-instillation microfluidic eyedrop patch for space medicine, Sensors and Actuators B: Chemical (2026). DOI: 10.1016/j.snb.2026.140885
Key concepts
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Using eyedrops in space—wearable patch offers a new approach (2026, October 20)
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