Electrical signals control many activities in the human body, from the exchange of messages between brain neurons and heart muscle impulses to the movements that enable arms and legs to move, among many other examples. . To monitor or modify these signals for medical purposes, a biocompatible and biodegradable optical fiber, based on agar, a material extracted from Gracilaria seaweed, has just been developed.
The research was led by Professor Eric Fujiwara of the State University of Campinas School of Mechanical Engineering (FEM-UNICAMP) in the state of São Paulo, Brazil. Cristiano Monteiro de Barros Cordeiro at the Gleb Wataghin Institute of Physics (IFGW-UNICAMP); and Hiromasa Oko at Gunma University in Japan. I have published an article about it. Scientific reports.
“Biocompatible devices are indispensable when fiber optics are used in medical applications such as vitals monitoring, phototherapy or optogenetics (a method combining optics, genetics and bioengineering to control and monitor specific cells). , among others. Also an alternative to existing telecommunication technologies based on glass or plastic fibers,” said Fujiwara.
The novel optical fiber was developed from agar, a natural gelatin obtained from red algae. It is transparent, flexible, edible and renewable. The same researchers previously developed an agar-based biocompatible optical fiber as a sensor for monitoring chemical concentrations and humidity.
“The manufacturing process basically consists of filling cylindrical molds with an agar solution. Our latest research broadens the range of applications, proposing a new type of optical sensor that detects the electrical conductivity of agar. takes advantage of conductivity,” Fujiwara explained.
When the fiber is excited by coherent light, it produces granular light patterns that evolve spatially and temporally. As electrical currents in the medium traverse the fiber, they modulate the refractive index of the agar and create a disrupted granular pattern, known as a stain.
“Analysis of these impedances enables us to determine the magnitude and direction of electrical impulses with reliable measurements for currents equal to or smaller than 100 microamperes (μA),” Fujiwara said.
The ability to detect electrical signals so subtle that they could be essential for potential biomedical applications. “The fiber can be used in a sensor system to monitor bioelectrical impulses generated in the brain or muscles, serving as a biodegradable alternative to traditional electrodes. A human-computer connection for assistive or rehabilitation technologies. I fiber as a sub-interface,” said Fujiwara.
The sensor’s response can be enhanced by adjusting the chemical composition of the material, and agar’s ability to mold into different geometries means it can be used to make lenses and other optical devices with sensitivity to electric current. The most important advantage is that the fiber can be absorbed by the body after consumption, avoiding the need for additional surgical intervention.
This is still bench research, Fujiwara stressed, and technical applications are far off, but rigorous determination of the physical parameters of the optical response to electric current would lay a solid foundation for future construction of biomedical devices using fiber. Is.
More information:
Eric Fujiwara et al., An Agar-Based Optical Sensor for Electrical Current Measurement, Scientific reports (2023). DOI: 10.1038/s41598-023-40749-7
Journal Information:
Scientific reports
By José Tadeu Arantes, FAPESP