2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
American researchers have developed a biocompatible implantable device that can measure tension and pressure, and after a specified time dissolve in the body. Due to this, the device can not be removed after surgery, say the developers in the journal Nature Electronics.
Implantable sensors make it possible to fairly accurately monitor the course of treatment or the patient's condition, measuring the parameters of specific parts of the body. But they have an obvious drawback - if the device does not need to be used constantly, like, for example, a pacemaker, another operation is required to remove it. In the new work, the scientists described the creation and testing of a sensor that can measure tension and pressure, which can be useful, for example, in the treatment of tendon injuries.
Researchers led by Zhenan Bao of Stanford University have developed a biocompatible device that can independently measure pressure and stretch, and dissolve after use for its design life. It consists of several layers that together form two sensors. Two layers with magnesium electrodes, insulated with polymer layers, can move relative to each other, thereby changing capacitance and showing stretching. The other part of the layers forms a capacitive pressure sensor. It consists of two electrodes separated by a well-compressible dielectric layer. When the sensor is compressed, the distance between the electrodes decreases, which leads to a change in capacitance, which can also be measured. Outside, all these layers are covered with a biodegradable polymer, which protects the internal structure of the device from premature destruction.
The stretch sensor can measure up to 15 percent stretch, and the pressure sensor operates from zero to 100 kilopascals. The researchers suggested using the device to measure the parameters and loads on the tendons in the treatment of their injuries. They conducted laboratory tests of the device in an environment that simulates a living organism (temperature 37 degrees Celsius and sodium phosphate buffer). It turned out that the device is able to work stably for two to three weeks in such conditions without significant changes in sensitivity - usually this period is enough to heal tendon injuries.
In addition, the developers tested the device on a rat by implanting a sensor in its back. The sensor sensitivity results were similar - they began to change noticeably after two weeks of observations. The authors also evaluated the biocompatibility of the device. They observed an inflammatory response at the implantation site only during the first week, and in the next seven weeks, it was no longer observed. It is worth noting that while the development of scientists has an important drawback - only the device itself is soluble and biocompatible, but it is necessary to take readings from it using separate electrodes. In the future, the authors are going to develop a completely biodegradable system for wireless transmission of collected data.
In 2016, another group of American scientists developed multifunctional sensors implanted in the brain, which can also be absorbed over time. Depending on the configuration, they can measure pressure, fluid flow, temperature and acidity.