Sweat-Collecting Patch Influenced By Cactus Spines Could Make Blood Pricking For Diabetics Unnecessary


According to the Centers for Disease Control and Prevention (CDC), at least 34.2 million Americans are living with diabetes, while 88 million American adults have prediabetes. With such a large number of individuals dealing with this chronic disease, treatments and means of dealing with this lifelong disease are always in the imminent.

In yet another move forward in the treatment of diabetes patients, a new sweat-collecting patch was developed by a research team that found inspiration from a cactus, and how its spines manage to attract water.

Since sweat is one of the most effective bodily fluids that can be used to analyze bioanalytes in the body without having to collect a person’s blood. What this means is that this sweat sensor will lessen the inconvenience that diabetic patients deal with every day, having to draw their blood repeatedly. They can also be used as wearable devices for a individuals’ daily healthcare monitoring.

One issue with these sweat sensor patches, however, is that they can be impeded by low or irregular sweat-secretion rates in patients.

The research team, which was led by Professor Kilwon Cho and Ph.D. candidate Johghyun Son of POSTECH’s Department of Chemical Engineering, have recently created a skin-attachable patch that has the ability to collect sweat by mimicking the same principle that cactus spines use to draw in water.

In order to survive, cacti – which grow in extremely dry environments – have the ability to move water droplets from the tip of their spines to their base in order to survive. This phenomenon is called Laplace pressure, which is when fine water droplets move because of the difference in pressure that acts on the inside and outside of the curved surface of the water droplet.

With this new patch developed by Professor Kilwon Cho and his team, they applied this same principle that cactus spines use to collect water. The team copied the same structure of the cactus spine, ‘using the wedge-shaped wettability patterns with superhydrophobic / superhydrophilic surfaces.’

Because of this process, a sweat droplet on the wedge-patterned surface instinctively moves to the broad end of the wedge pattern due to the Laplace pressure, where a difference between the front and back surfaces of the droplet are maximized.

What these research tests confirm is that the wedge-patterned channel has the ability to quickly and simultaneously collect sweat despite the inclination of the microfluidic channels, without requiring any added or supplementary force.

Moreover, the wedge-patterned channel has shown incredible efficiency at collecting sweat as it transfers or carries almost all of the sweat droplets to the sensing area, without having to leave too much behind inside the channel. This enables it to gather the sweat much faster as well, in comparison to the conventional microfluidic channels. It also allows the patch to continually monitor the bioanalytes within the blood.

Professor Kilwon Cho of POSTECH explained, “Difficulties in collecting sweat has hindered its use in wearable healthcare devices. This newly developed patch solves that issue by quickly collecting sweat and facilitating its use in various wearable healthcare devices, including blood sugar monitoring.”