Swallow the electrical stimulator
The swallowed capsule with an electrostimulator was tested in a pig's stomach
Grigory Kopiev, N+1
Engineers from the USA, Denmark and Sweden have created a prototype capsule for electrical stimulation of the stomach wall. It is packed in a soluble shell and enters the stomach when swallowed. After dissolving the shell, the capsule inserts electrodes into the stomach wall, and then can detach to complete the work and exit the body. The developers tested the prototype on a pig and a model of a human stomach, and also showed that the pulses of the device can be read using subcutaneous electrodes. An article about the device and its testing is published in Science Advances (Abramson et al., Ingestible transiently anchoring electronics for microstimulation and conductive signaling).
Some people have gastroparesis or similar disorders due to various reasons, in which the activity of the stomach muscles decreases. One of the ways to treat these conditions is to implant a small device next to the stomach, which, with the help of electrical stimulation, causes the muscles to contract. As with other implants (for example, pacemakers), its installation takes place during surgery, which always involves some risk.
In the last few years, scientists have been developing swallowable devices in the form of capsules designed to diagnose or treat diseases of the gastrointestinal tract. One of these devices was presented last year by a group led by Giovanni Traverso from the Massachusetts Institute of Technology. That device was made in the form of an egg-shaped capsule with a heavy steel base, thanks to which the capsule was oriented vertically after entering the stomach. Inside the capsule there was a spring, triggered a few minutes after contact with gastric juice, and a needle attached to it.
In the new work, Traverso's group used the old design, but applied it to a new task — inserting stimulating electrodes into the stomach wall. In the new capsule, as in the previous version, there is a spring that is fixed in a compressed state with the help of isomaltite, which is usually used as a sweetener or a base for lollipops. After getting into the stomach, isomaltite dissolves in a few minutes and the spring is straightened.
The scheme of operation of the device and its design.
When the spring is straightened, it pushes forward two electrodes that enter the mucous membrane, but do not reach the deep layers of the stomach wall. The electrodes are connected to the control unit, which is connected to the capsule by wires. The unit has a battery and a microcontroller that controls impulses that cause contractions of the gastric muscles. Before taking the device, the stimulating capsule together with the block are placed in a standard capsule for medicines of size 000 (26.1 millimeters in length and 9.9 in diameter). Five minutes after entering the stomach, it almost completely dissolves.
Another feature of the development is that the developers have learned to observe the operation of the device without using the communication module. Instead, they suggested tracking electrical impulses using subcutaneous electrodes on the arm or in another part of the body.
The authors tested the device's operation in vivo on a pig and ex vivo in a human stomach. Tests have shown that after getting into the stomach, capsules are oriented in it properly and after 5-15 minutes, electrodes are inserted into the mucous membrane. Engineers confirmed the correct operation of the device in two ways: by registering electrical impulses through subcutaneous electrodes, and also by seeing rhythmic contractions of the gastric muscles using an ultrasound probe.
However, the device cannot be considered ready for use or even for tests on living people yet. For example, the authors admit that in this work they did not set the task of developing a method for separating the capsule from the stomach wall and safely removing it through the gastrointestinal tract. But they noted that in future versions this can be solved by using an actuator to pull the electrodes back into the capsule or electrode material that would dissolve after a while.
Recently, Chinese scientists have presented another non-invasive device for the treatment of disorders and diseases of the stomach. They created an endoscope with a 3D printer at the end, which can print layered "patches" on wounds of the gastric wall, using hydrogels with epithelial and muscle cells.
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