Wearable sweat detector to detect uric acids that cause gout (gout)

Scientists have succeeded in developing an easier method to mass-produce highly accurate sweat detectors capable of detecting a variety of compounds present in low concentrations, compounds associated with medical conditions

[Translation by Dr. Nachmani Moshe]

There are many things we dislike when we go to the doctor: co-paying for medical services, long waits in the waiting room, out-of-date periodicals, sick people coughing on us without covering their mouths, and more. For many, it turns out, the worst thing about visiting a doctor is getting stuck with a syringe. Blood tests are a tested and proven method of assessing the situation inside our body, but the discomfort is inevitable. Or maybe it can be prevented, according to scientists from the California Institute of Technology (Caltech).

In a new article published in the scientific journal Nature Biotechnology, researchers describe a wearable detector that can be mass-produced, a detector that can detect minute levels of metabolites and nutrients in human blood, by examining and analyzing the composition of sweat. Sweat detectors developed in the past mainly focus on compounds found in the blood in high concentrations, such as salts, glucose and lactic acid. The researchers' innovative sweat detector is more sensitive than existing devices and can detect compounds in sweat that are in much lower concentrations than usual, and in addition, it is simpler to manufacture, according to the researchers.

The development of this type of detectors will allow doctors to continuously monitor the condition of patients with heart disease, diabetes, or kidney-related diseases, all of which are manifested by abnormal levels of nutrients or metabolites in the bloodstream. Patients will be able to benefit from a situation where their doctor obtains much more accurate information about their condition, while avoiding invasive and painful encounters with needles. "Wearable sweat detectors of this type have the ability to detect changes in health at the molecular level quickly, continuously and non-invasively," explains the lead researcher. "Such detectors could enable personalized monitoring and early diagnosis within a short time intervention."

The current research focuses on the development of devices based on microflow, the name of a technology that utilizes small amounts of liquid, usually through channels that are less than a quarter of a millimeter thick. Microflow is an ideal method for such an application as it minimizes the effect of sweat evaporation and skin contamination on measurement accuracy. As freshly supplied sweat flows through the microchannels, the device can obtain more accurate measurements of the composition of the sweat and can detect temporary changes in the concentrations of the substances within it.

To date, the researchers explain, wearable detectors based on microflow have been created mainly through a process of evaporation-lithography, a process that requires complex and expensive manufacturing processes. The research team decided, instead, to base their biodetectors on graphene, a form of carbon composed of a single layer. Both the graphene-based detectors and the tiny microflow channels are created by etching the plastic layers with a carbon dioxide laser, a device now so common that it's even available to home hobbyists.

The research team preferred that their detector be able to measure the breathing rate, the heart rate, and the concentrations of the substances uric acid and tyrosine. The researchers chose the substance tyrosine because it is able to be a marker for metabolic diseases, liver disease, eating disorders and neuropsychiatric conditions. Uric acid was chosen because in high concentrations it is associated with gout, a painful joint disease whose scope is increasing worldwide. Gout develops when high concentrations of uric acid in the body begin to crystallize in the joints, especially in the joints of the feet, causing itching and inflammation.

In order to test the performance of the detector, the researchers ran a series of experiments among healthy people and among patients. In order to measure the concentrations of tyrosine in sweat, which are affected by a person's physical fitness, the researchers chose two groups of people: trained athletes and people with normal physical fitness. As expected, the detector showed small concentrations of tyrosine in the sweat of the athletes. In order to measure the concentrations of uric acid, the researchers selected a group of healthy people and monitored the composition of their sweat while fasting, as well as after they ate a meal rich in purines, compounds found in food that break down in the body into uric acid. The detector showed that uric acid concentrations increased after the meal. The research team also performed a similar experiment among gout patients. Their uric acid concentrations, the detector showed, were higher than those measured in healthy subjects. In order to test the accuracy of the detectors, the researchers also took blood samples from the gout patients and the healthy subjects. The measurements made by the detector regarding the uric acid clearly matched the concentrations of the compound in the blood.

The lead researcher claims that the high sensitivity of the innovative detectors, along with the simplicity of their production, mean that they will eventually be able to be used by patients in their own homes to monitor medical conditions such as gout, diabetes and even heart disease. Receiving accurate and real-time information regarding their health will allow patients to actually adjust the dosages of the medications they take and their diet, according to the measurements. "Given that nutrients and metabolites present in our bodies at abnormal levels are associated with several health conditions, the information gathered from such wearable detectors will be valuable for both research and medical treatment," says the lead researcher.

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