At present, Gao Wei (transliteration), associate professor of medical engineering at the California Institute of Technology, and his colleague JoAnne Willens (JoAnne Willens) have developed a wearable sensor focused on medical applications after years of research and development. The most accurate and sensitive technology iteration to date.
Pictured is the sweat monitoring sensor, and the larger bend is the electrode that stimulates perspiration.
Willens said: “We have designed wearable sweat sensors before, but there are many biological indicators that need to be detected. We have not been able to technically implement them before, and there is no better strategic plan. Previously designed wearable sweat sensors rely on embedded in them. Enzymatic substances to detect a limited number of related compounds, although the antibodies used in the sensor can detect more chemical compounds in low concentration samples, but this technology has a big disadvantage – the antibody in the sensor can only be used once , which would mean that the sensor is a high-loss device and not very practical.”
The latest design of the wearable sensor has undergone significant upgrades, including: Molecularly imprinted polymer technology, which is like a man-made, reusable antibody. To give a more in-depth look at how the sensor works, they explain, Imagine there is an object shaped like a plus sign, if you pour silicone rubber on that object, harden the rubber, and then separate the molecules from the rubber, you get a plus-shaped hollow block of rubber, only the same size and The shape of the object can match this hollow structure well, which is how molecularly imprinted polymers work, but the size is much smaller. For example: if one wants to make a sensor that can detect glutamine amino acid, one needs to make a polymer containing glutamine molecules, and then chemically remove the glutamine, which results in a polymer with holes, forming a Glutamine is exactly the same.
The innovation of the newly designed wearable sensor is that the polymer formed by this special condition can be combined with a material that is oxidized or reduced under an applied voltage when it comes into contact with human sweat.
The innovation of the wearable sensor designed by Gao Wei is that the polymer formed by this special condition can be combined with a material, which will be oxidized or reduced under the applied voltage when it comes into contact with human sweat. As long as these glutamine-shaped pores are open, sweat reaches the inner layer of the sensor and generates an electrical signal. But when the glutamine molecule comes into contact with the polymer, it enters the pore-like structure.
When these pores are blocked by glutamine molecules, there will be less access to the inner layer of sweat, and the corresponding electrical signal will become weaker. By monitoring the changes in the electrical signal, researchers can infer how much glutamine is contained in human sweat. Amide, the more glutamine, the weaker the signal, and the less glutamine, the stronger the signal.
“This unique strategy allows us to detect all nine essential amino acids and multivitamins in the human body, which we can continuously monitor, and unlike antibodies, the polymers in the sensor can be easily ‘washed’,” said Gao Wei. A weak electrical signal is applied to destroy the target molecule or to empty the pore it is in.”
The sensor’s second innovation is microfluidics, a technique for manipulating small amounts of fluid using tiny channels less than 0.25 millimeters in diameter. Microfluidic technology 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 expel drug molecules from the body through electric current, but the previous sensor requires more sweat and therefore more electric current, which may make users feel uncomfortable, due to microfluidics and Using a different type of drug, the new sensor requires less human sweat, while the current required 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 manga “The Monster of the Amikaga Fault.”
“This microfluidic design allows us to use less current, and we can use tens of microamps of current to generate sweat equivalent to 4-5 hours of stimulation for a few minutes,” said Gao. The sensor technology has been tested in human trials in a laboratory setting, 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 in the intake of nutrients when we eat food. It not only monitors nutrients, but also monitors hormone and drug levels in the body. Continuous monitoring of multiple health conditions.
The paper, titled “Wearable Electrochemical Biosensors to Monitor Metabolites and Nutrients,” was published in the Aug. 15 issue of Nature Biomedical Engineering.