There are numerous things to dislike about going to the doctor: Paying a copay, sitting in the waiting room, out-of-date magazines, sick people coughing without covering their mouths. For many, though, the worst thing about a doctor's visit is getting stuck with a needle. Blood tests are a tried-and-true way of evaluating what is going on with your body, but the discomfort is unavoidable. Or maybe not, say Caltech scientists.
In a new paper published in Nature Biotechnology, researchers led by Wei Gao, assistant professor of medical engineering, describe a mass-producible wearable sensor that can monitor levels of metabolites and nutrients in a person's blood by analyzing their sweat.
Previously developed sweat sensors mostly target compounds that appear in high concentrations, such as electrolytes, glucose, and lactate. Gao's sweat sensor is more sensitive than current devices and can detect sweat compounds of much lower concentrations, in addition to being easier to manufacture, the researchers say.
The development of such sensors would allow doctors to continuously monitor the condition of patients with illnesses like cardiovascular disease, diabetes, or kidney disease, all of which result in abnormal levels of nutrients or metabolites in the bloodstream.
Patients would benefit from having their physician better informed of their condition, while also avoiding invasive and painful encounters with hypodermic needles.
"Such wearable sweat sensors have the potential to rapidly, continuously, and noninvasively capture changes in health at molecular levels," Gao says. "They could enable personalized monitoring, early diagnosis, and timely intervention."
Gao's work is focused on developing devices based on microfluidics, a name for technologies that manipulate tiny amounts of liquids, usually through channels less than a quarter of a millimeter in width.
Microfluidics are ideal for an application of this sort because they minimize the influence of sweat evaporation and skin contamination on the sensing accuracy. As freshly supplied sweat flows through the microchannels, the device can make more accurate measurements of sweat and can capture temporal changes in concentrations.
Until now, Gao and his colleagues say, microfluidic-based wearable sensors were mostly fabricated with a lithography-evaporation process, which requires complicated and expensive fabrication processes. His team instead opted to make their biosensors out of graphene, a sheet-like form of carbon.
Both the graphene-based sensors and the tiny microfluidics channels are created by engraving the plastic sheets with a carbon dioxide laser, a device that is now so common that it is available to home hobbyists.
The research team opted to have their sensor measure respiratory rate, heart rate, and levels of uric acid and tyrosine. Tyrosine was chosen because it can be an indicator of metabolic disorders, liver disease, eating disorders, and neuropsychiatric conditions.
Uric acid was chosen because, at elevated levels, it is associated with gout, a painful joint condition that is on the rise globally. Gout occurs when high levels of uric acid in the body begin crystallizing in the joints, particularly those of the feet, causing irritation and inflammation.
To see how well the sensors performed, the researchers ran a series of tests with healthy individuals and patients. To check sweat tyrosine levels, which are influenced by a person's physical fitness, they used two groups of people: trained athletes and individuals of average fitness.
As expected, the sensors showed lower levels of tyrosine in the sweat of the athletes. To check uric acid levels, they took a group of healthy individuals and monitored their sweat while they were fasting as well as after they ate a meal rich in purines, compounds in food that are metabolized into uric acid.
The sensor showed uric acid levels rising after the meal. Gao's team also performed a similar test with gout patients. Their uric acid levels, the sensor showed, were much higher than those of healthy people.
To check the accuracy of the sensors, the researchers also drew blood samples from the gout patients and healthy subjects. The sensors' measurements of uric acid levels strongly correlated with levels of the compound in the blood.
Gao says the high sensitivity of the sensors, along with the ease with which they can be manufactured, means they could eventually be used by patients at home to monitor conditions like gout, diabetes, and cardiovascular diseases. Having accurate real-time information about their health could even allow a patient to adjust their own medication levels and diet as required.
"Considering that abnormal circulating nutrients and metabolites are related to a number of health conditions, the information collected from such wearable sensors will be invaluable for both research and medical treatment," Gao says.
The paper describing the research, titled, "A laser-engraved wearable sensor for sensitive detection of uric acid and tyrosine in sweat," appears in the Nov. 25 issue of Nature Biotechnology. Co-authors are Yiran Yang (MS '18), Yu Song, Xiangjie Bo, Jihong Min (MS '19), Minqiang Wang, Jiaobing Tu, and Adam Kogan of Caltech; Haixia Zhang of Peking University; On Shun Pak of Santa Clara University; Lailai Zhu of Princeton; and Tzung K. Hsiai and Zhaoping Li of UCLA. Hsiai is also a visiting associate at Caltech.
Funding for the research was provided by the Rothenberg Innovation Initiative program, the Carver Mead New Adventures Fund, and the American Heart Association.
Emily Velasco | EurekAlert!
How do scars form? Fascia function as a repository of mobile scar tissue
28.11.2019 | Helmholtz Zentrum München - German Research Center for Environmental Health
Helper protein worsens diabetic eye disease
28.11.2019 | Johns Hopkins Medicine
Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.
Fibroblasts kit - ready to heal wounds
Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.
In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...
Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.
Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...
Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.
By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...
15.11.2019 | Event News
15.11.2019 | Event News
05.11.2019 | Event News
29.11.2019 | Life Sciences
29.11.2019 | Life Sciences
29.11.2019 | Life Sciences