Shulou(Shulou.com)11/24 Report--

On the morning of August 19, Beijing time, it is reported that if you have ever taken blood, whether it is to check your cholesterol, kidney function, hormone index, blood sugar, or as part of a comprehensive physical examination, you may wonder-- Why do you have to draw blood to test the relevant body mass index? Isn't there a simpler and less painful way?

At present, after years of research and design, Gao Wei, associate professor of medical engineering at the California Institute of Technology, and colleagues such as JoAnne Willens, have recently developed a wearable sensor focused on medical applications, which represents the most accurate and sensitive technology iteration to date.

The picture shows a sweat monitoring sensor, and the larger bend is the electrode that stimulates perspiration.

"We have designed wearable sweat sensors before, but there are a lot of biological indicators that need to be detected," Willens said. "We can't achieve it technically before, and we don't have a better strategy. The previously designed wearable sweat sensor relies on embedded enzymes to detect a limited number of related compounds, although antibodies used in the sensor can detect more compounds in low concentration samples. However, this technology has a big disadvantage-the antibody in the sensor can only be used once, which will mean that the sensor is a high-loss device and is not practical. "

The newly designed wearable sensor has been greatly upgraded, including molecularly imprinted polymer technology, which is like an artificial, reusable antibody. In order to explain more deeply how the sensor works, they explained that imagine an object in the shape of a plus sign, if silicone rubber is dumped on the object to harden the rubber, and then the molecules are separated from the rubber. You will get a hollow rubber block in the shape of a plus sign, and only objects of the same size and shape can well match this hollow structure, which is how molecularly imprinted polymers work, but the size is much smaller. For example, if people want to build a sensor that can detect glutamyl amino acids, they need to prepare a polymer containing glutamine molecules, and then remove glutamine through a chemical process, so that a porous polymer can be obtained. the formation is exactly the same as glutamine.

The innovation of the newly designed wearable sensor is that the polymer formed under this special condition can be combined with a material that is oxidized or reduced under applied voltage when in contact with human sweat.

The innovation of Gao Wei's wearable sensor is that the polymer formed under this special condition can be combined with a material that is oxidized or reduced under applied voltage when in contact with human sweat. As long as these glutamine-shaped holes are open, the sweat touches the inner layer of the sensor and produces electrical signals. But when the glutamine molecule comes into contact with the polymer, it enters the porous structure.

When these pores are blocked by glutamine molecules, there is less contact with the inner layer of sweat, and the corresponding electrical signals become weaker. By monitoring changes in electrical signals, researchers can infer how much glutamine is in human sweat. The more glutamine, the weaker the signal, the less glutamine, the stronger the signal.

"this unique strategy enables us to detect all nine essential amino acids and multivitamins in the human body, and we can monitor them continuously," Gao said. "unlike antibodies, the polymer in the sensor can be easily 'cleaned'. Destroy the target molecule or empty its hole by using a weak electrical signal."

The second innovation of the sensor is the application of microfluidic, a technology that uses tiny channels less than 0.25 mm in diameter to manipulate a small amount of fluid, which allows the sensor to work in the presence of trace amounts of sweat.

Gao Wei pointed out that the human body can use artificial stimulation to get drug molecules out of the body through electric current, but previous sensors need more sweat, so they need more current, which may make users feel uncomfortable. Due to microfluidic and the use of different types of drugs, the new sensor requires less human sweat, and the current that needs to produce sweat may be very small.

A glutamine molecule is slipping into a hole-like structure specially designed for it, similar to the plot in Junji Ito's cartoon "the Monster of the Ami Shell Fault".

"this microfluidic design allows us to use less current, and we can use dozens of microamperes to stimulate it for a few minutes to produce the equivalent of 4-5 hours of sweat," Gao said. so far, this sensor technology has been tested in human trials in a laboratory environment, and we hope to have a wider range of testing applications in the future. "

This method can detect some new key nutrients and metabolites, so that we can monitor the changes of nutrients intake when we eat food. It can monitor not only nutrients, but also hormone and drug levels in the body. A variety of health conditions can also be continuously monitored.

Currently, the article, "wearable Electrochemical biosensors that can monitor metabolites and nutrients," is published in the August 15 issue of the Journal of Natural Biomedical Engineering.

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