first-of-its-kind soft, thin and flexible microfluidic
device that easily adheres to the skin and analyzes the wearer's sweat has been developed by researchers
. The sweat-sensing skin patch
that connects wirelessly with a smartphone may soon be able to track health
during exercise and warn against dehydration.
It provides results similar to conventional
laboratory testing and adheres to the skin even under complex conditions. This research is published in Science
‘Now wear a personal laboratory up your sleeve.’
Sweat-Sensing Skin Patch
Sweat is composed
of chemical compounds that provide physiological
health information. The researchers developed a skin-like stretchable wearable electronic
device that analyses sweat components.
This device is simple to use,
affordable and flexible, moving naturally with the skin. It
is only slightly bigger than a quarter and has the same thickness. It is designed for a single use of a few hours. It
is placed directly on the skin of the forearm or back.
The device has a complex
network of microfluidic channels and storage reservoirs, for analysis of sweat. It has four different small,
circular compartments, into which the sweat is collected through tiny,
microscopic channels during moderate-to-severe physical activity.
The compartments have chemical reagents with which the sweat reacts. This result in visible color changes in ways that quantitatively relate
to pH and concentrations of glucose, chloride and lactate in the sweat.
The device thus lets the wearer know
if he/she is suffering from dehydration and if the levels of water and
electrolytes need to the replenished without the need for a blood test. It also
helps to detect the biomarker for cystic fibrosis
"The intimate skin interface
created by this wearable, skin-like microfluidic system enables new measurement
capabilities not possible with the kinds of absorbent pads and sponges
currently used in sweat collection," said John A. Rogers, from
the Northwestern University Feinberg School of Medicine, who led the research team that created the 'lab on the skin.'
Testing the Sweat Patch
In a study to test the device, 21
healthy volunteers were recruited. The device was
tested in two different conditions:
- On nine healthy volunteers during cycling
indoors in a fitness center under controlled conditions
twelve participants of a
long-distance bicycle race in arid and complex conditions,
mimicking 'real-world' setting
was placed on the arms and backs of the volunteers to capture sweat. It successfully
collected sweat and captured key markers, ranging from sweat rate to glucose
The researchers analyzed the sweat for biomarkers, by capturing a picture of the sweat
patch using a smartphone. They used an image processing software app and wireless data transmission to convert the data.
Similarity in Readouts
In the group that cycled indoors-
When researchers analyzed the biomarker readouts from
the device, it was very similar to the results obtained through conventional laboratory analysis of the same sweat.
With the long-distance cyclists-
cyclists, the researchers found the device to be robust even under harsh
conditions. The device stayed in place without causing
discomfort or irritation. It did not leak and provided the kind of quality
information the researchers sought.
The sweat analysis device has
the following features:
- The device captures, stores and analyzes sweat quickly and on-the-spot.
- The device can determine biomarker levels and tracks health during
- A smartphone camera and app are
used to read the biomarker levels.
future, the researchers hope to extend their technology to other
fluids, such as tears and saliva.
- Koh A et al. A soft, wearable
microfluidic device for the capture, storage, and colorimetric sensing of
sweat. Science Translational Medicine 2016: Vol. 8, Issue 366, pp. 366ra165 DOI: 10.1126/scitranslmed.aaf2593