Soft robots made using 3D printing may offer unique advantages for medical applications but many challenges remain before they reach clinical use, according to researchers from South Korea’s Jeju National University.

The review, published in the journal Science and Technology of Advanced Materials, found that 3D printing is well suited to building robots that have complex external shapes together with an internal porous structure.

These soft robots could be used in various ways to assist medical care. Inside the body, a 3D-printed soft silicone pump could be used as an artificial heart, or ‘micro-biobots’ that travel through blood vessels could be used to deliver drugs.

Outside of the body, soft robots are being developed for prosthetics, monitoring vital signs, and for organ-on-a-chip devices to replace testing on animals.

There are many 3D printing techniques available, but all follow the same basic principle of converting digital data into three-dimensional objects by layering a material until the object is fabricated.

Making soft robots with highly compliant materials such as fluids, gels and polymers allows them to mimic functions present in living organisms. In the last few years, there has been a significant trend towards using 3D printing for their manufacturing instead of conventional moulding and casting approaches.

However, the review found that there are many challenges that need to be surmounted before widespread clinical use, including overcoming major research gaps, ensuring materials do not shrink during the solidification process and speeding up the process for mass production.

The paper stated that ‘commercial success depends on new innovation in soft lithography, 3D printing and other rapid prototyping technologies to mass produce soft structures and robots that are inexpensive and satisfy market demand.’

Recently, Harvard researchers developed sensors for soft robots that allow it to detect movement, pressure, touch and temperature.