A South Korean research team has developed a wearable patch that delivers eye drops without relying on gravity. Pressing a button triggers a chemical reaction inside the patch, and the resulting gas pressure pushes the liquid out. The technology is expected to help astronauts manage their eye health and to assist patients who cannot apply eye drops on their own.
The Korea Advanced Institute of Science and Technology (KAIST) said on the 21st that a team led by Professor Ki-Hun Jeong of its Department of Bio and Brain Engineering developed the wearable eye-drop delivery patch jointly with a team led by Professor Woo Se-joon of Seoul National University Bundang Hospital, taking into account the constraints of the space environment.
Eye drops are normally administered by letting a droplet fall from a bottle into the eye. Gravity and the user's posture can cause the liquid to run outside the eye or miss the intended spot, making the process inconvenient. The problem is more acute in space, where microgravity keeps liquids from falling downward, making the conventional method difficult. Long-duration space exploration requires compact devices that allow astronauts to medicate themselves without direct help from medical staff.
The patch consists of a chamber that holds the eye drops and a narrow channel through which the liquid flows out. The user attaches the patch near the eye and presses a button, setting off a chemical reaction that generates gas inside. The pressure from that gas forces the eye drops out through the channel and into the eye.
The driving force comes from carbon dioxide produced when ascorbic acid, or vitamin C, and sodium bicarbonate, the main ingredient in baking soda, come into contact with water. A filter placed between the reaction chamber and the drug reservoir allows gas to pass through while blocking liquid, keeping the reactants separate from the eye drops while transmitting pressure. Because the design requires no external pump or electrical actuator, it can be used in settings where operating medical equipment is difficult.
In tests conducted with the patch oriented in different directions relative to gravity, the team confirmed that it maintained consistent delivery performance. In evaluations on human subjects, the researchers used artificial tears containing a fluorescent marker to compare delivery patterns between the patch and conventional instillation. The patch achieved delivery performance comparable to that of the conventional method.
The patch could serve as a compact, portable drug-delivery technology for individual use in space, where direct access to medical personnel is limited and medical equipment is difficult to operate. On the ground, it is expected to help people medicate themselves when hand tremors, as in Parkinson's disease, or other physical limitations make it hard to position an eye-drop bottle over the eye.
The technology has not yet been validated for use in an actual space environment. Commercialization will require further testing under simulated space conditions, along with verification of safety over repeated use, long-term drug storage stability and compatibility with various eye-drop formulations. The team plans to carry out validation using actual pharmaceutical products and to assess long-term use.
"The flexible eye-drop injection patch developed in this study is a wearable platform that can deliver drugs without separate, complex equipment," Jeong said. "We expect it can be extended to medical technologies for a range of environments, including space medicine."