MIT engineer develops color-changing fiber optic sensor

[ China Instrument Network Instrument Development ] Compression bandages are commonly used to apply pressure to a patient's limb to improve blood flow and reduce swelling of the patient's limb. According to different conditions need to apply different sizes of pressure, but there is no reliable method can be used to measure the pressure required to apply pressure during treatment. Recently, a team of researchers from the Massachusetts Institute of Technology designed a biomimetic optomechanical fiber that can change color based on pressure and strain and that can be used as a pressure sensor in compression bandages.

The color of photoelectron bionic fibers developed by the Massachusetts Institute of Technology depends on how light is emitted in its internal, periodic structure. By changing the shape of the fiber, such as stretching it, the color of the fiber can be adjusted in a predictable manner. The research team believes that its development of stretchable optomechanical fibers will become standard compression bandages in the future, which will allow medical service providers to more easily provide the best pressure for the patient's specific situation.

Bionic design of opto-mechanical sensors

The researchers said that the color of the structure found in nature today is not made of dyes or pigments. On the contrary, the cause of the color of the structure is caused by the interference of scattered light from the nanostructures in the material at different wavelengths. The interfering light enters the viewer's eye as a color of light whose color can change depending on the viewing angle or in response to changes in the shape of the material.

The MIT research team applied naturally occurring structural colors to the design of pressure-sensing optomechanical fibers. The fiber has a periodic structure consisting of two thin, transparent polymers of polydimethylsiloxane (PDMS) and polystyrene polyisoprene triblock polymer (PSPI), in black polydimethylsiloxane. The oxyalkylene cores are stacked 30 to 60 times around and the resulting fiber thickness is about 10 times the diameter of the human hair filament. The periodic structure stacked by PDMS/PSPI acts as a Bragg reflector and can strongly reflect visible light in a narrow wavelength range.

The color of the light reflected from the periodically stacked fibers depends on the nanostructure of each layer. As the fiber is stretched, the number of cycles of the fiber layer decreases, which in turn changes the color of the fiber from red (unstrained) to orange, yellow, green, and finally blue (maximum strain). The researchers pointed out that it is possible to design fibers with different reflection peaks to make a pressure-sensitive fiber that changes its color from blue to red as strain pressure increases.

The researchers measured quantitative measurements of fiber optic mechanical properties to show that the bionic fiber can be stretched to more than twice its original length, and after 10,000 cycles of stretching, the fiber still produces consistent and highly visible colors. .

Optical fiber sensor demonstration experiment

To demonstrate pressure sensing during compression therapy, MIT researchers stitched a stretchable optomechanical fiber along the length of a standard compression bandage. They also created a chart that matched the color of the fibers with the amount of pressure that the bandage produced.

The researchers invited 12 untrained student volunteers to test the effectiveness of photoelectron bionic compression bandages. They provided student volunteers with two commonly used compression bandage systems, as well as MIT optoelectronic compression bandages and color charts. The results of this demonstration show that students who use photoelectron compression bandages and color charts are more likely to apply optimal pressure than when using two other traditional compression bandage systems.

Although the results of this preliminary study are encouraging, researchers say they need to find a more cost-effective way to produce their optoelectronic fiber bandages to make them suitable for medical textiles.

(Original title: Color-changing Fiber Optic Sensors for Medical Textiles)