3D bioprinting is an innovative process used to fabricate biomedical parts to create tissue-like structures through the use of bioink. This method mainly serves research purposes and drug development, and usually requires the use of large 3D printing machines to construct cellular compositions outside of the body. Now, a team of engineers have developed a miniature and flexible robotic arm that could be utilized to 3D print biomaterial directly onto organs within the human body. This soft robot can be inserted into the body in the same way as an endoscope and has the capacity to directly deliver multilayered biomaterials right onto the surface of internal organs and tissues.

Engineers at The University of New South Wales (UNSW, Sydney, NSW, Australia) have developed a proof-of-concept device, known as F3DB, that features a highly maneuverable swivel head that ‘prints’ the bioink, attached to the end of a long and flexible snake-like robotic arm, all of which can be controlled externally. The device features a three-axis printing head directly mounted onto the tip of a soft robotic arm. The printing head, which consists of soft artificial muscles that enable it to move in three directions, functions similarly to conventional desktop 3D printers. The soft robotic arm can bend and twist using hydraulics and can be fabricated at any length needed. Its stiffness can be finely tuned utilizing various types of elastic tubes and fabrics.

The printing nozzle can be programmed to print pre-determined shapes, or operated manually in situations demanding more complex or undetermined bioprinting. Additionally, the team used a machine learning-based controller to aid the printing process. After further development, medical professionals can use the technology to reach hard-to-reach areas within the body via small skin incisions or natural orifices.

The UNSW team further demonstrated the feasibility of the technology by testing the cell viability of living biomaterial after being printed via their system. The researchers tested their device inside an artificial colon, as well as by 3D printing various materials with different shapes on the surface of a pig’s kidney. Their experiments showed that the cells were not affected by the process, with most of the cells remaining alive post-printing. The cells continued to grow for the next seven days, and the team observed four times as many cells one week after printing.

The research team also demonstrated the potential of F3DB as an all-purpose endoscopic surgical device. They believe it would be particularly useful in performing endoscopic submucosal dissection (ESD) procedure to remove certain types of cancer, such as colorectal cancer. The nozzle of the F3DB printing head can be used as an electric scalpel to first mark and then cut away cancerous lesions. Water can be directed through the nozzle to simultaneously clean any blood and excess tissue from the site, while faster healing can be promoted by the immediate 3D printing of biomaterial directly while the robotic arm is still in place.

To further demonstrate the potential of F3DB as an all-in-one endoscopic surgical tool, the UNSW research team conducted experiments on a pig's intestine. The results are promising and the team has been granted a provisional patent for their device. The next step is to conduct in vivo tests on living animals in order to demonstrate its practicality. Furthermore, the researchers plan to integrate features such as a camera and real-time scanning system that would reconstruct the 3D tomography of the moving tissue inside the body.

“Existing 3D bioprinting techniques require biomaterials to be made outside the body and implanting that into a person would usually require large open-field open surgery which increases infection risks,” said Dr Thanh Nho Do, who led the new research from UNSW Medical Robotics Lab. “Our flexible 3D bioprinter means biomaterials can be directly delivered into the target tissue or organs with a minimally invasive approach. This system offers the potential for the precise reconstruction of three-dimensional wounds inside the body, such as gastric wall injuries or damage and disease inside the colon.” 

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