To create devices that can be used to monitor heart rate and stimulate nerves,a Chinese-led team of scientists claims to have developed a highly conductive 3D printing ink that can build circuits in hydrogel. The jelly-like hydrogel could also be enhanced with radio-frequency identification (RFID) chips,
which are also used in credit cards and pet microchips, to store data such as medical records, the researchers suggested.
They stated in an article published on December 19 in the peer-reviewed journal Nature Electronics that “hydrogel electronics are highly promising for biomedical applications due to their tissue-like softness and high water content.”
The method “should, thus, open up new design possibilities for soft, customisable,
3D hydrogel electronics for diagnostic and treatment devices,” the Chinese and Singaporean research team said.
A freeform 3d printing method
Unlike traditional 3D printing, which builds objects layer by layer, hydrogel allows for the free-form printing of 3D structures,
according to the study’s first author, Hui Yue, who was a postdoctoral research fellow at Westlake University’s engineering school in Hangzhou at the time.
Hui, who is currently a postdoctoral research fellow at the University of Adelaide in Australia,
claimed that building circuits in a 3D space are possible without the aid of outside resources.
A network of hydrophilic polymers called hydrogel is similar to biological tissue in that it can hold a lot of water. They must include stretchy, conductive materials if hydrogels are to be used to create electronic devices.
In the study, the researchers developed hydrogel electronics using silver, the most conductive metal,
as an ink and hydrogel as a supporting matrix. The finished product can be compressed, stretched, or twisted without losing its original shape.
Electrocardiography (ECG) electrodes, which record the electrical activity of the heart, were 3D printed by the team, and they discovered the signals had a higher resolution than electrodes that were already on the market.
Additionally, a millimetre-scale electrode was printed to stimulate mice’s sciatic nerve and cause movements in their hind limbs.
According to the study, the hydrogel device generated motion at an angle of 77 degrees, which was significantly greater than the 10-degree movement produced by conventional ionically conductive electrodes at the same voltage.
The conductivity of Ag-hydrogel ink
These findings demonstrate the printed Ag (silver)-hydrogel electrodes’ superior electrical-stimulating ability over those using ionically conductive materials,
according to the study’s authors.
The high conductivity of our Ag-hydrogel ink and the
“tight and conformal interfaces between the tissues and 3D printed electrodes” may be to blame for this.
To instruct muscles to contract,
the nervous system sends electrical signals. According to Hui,
the technology may be able to assist those who require external electrical stimulation for their nerves because of a condition or accident.
The group created a hydrogel RFID device that can be read by an industrial RFID reader and can withstand stretching.
A Medical record reader
According to Hui, it could be worn as a medical record reader for people who are ill or have conditions that require easy access to medical records,
as well as for pets or farm animals for identification.
According to him, the next step was to test the hydrogel’s longevity,
stability, and safety as an implant in animals over an extended period of months and years.
“We’ll examine whether the implant results in scarring or inflammation when it’s removed,” Hui said.
The goal of our research is to demonstrate that hydrogel is more biocompatible than other materials. We’ll investigate more of its possible uses while maintaining its security.
