A number of people dream that one day 3D printing will be used to create functional organs that can be transplanted into a human, solving the organ transplant shortage and help save millions of lives.

We are nowhere near that point, and may not be for decades, but the science is advancing.

The techniques used today to explore this possibility are often referred to as bioprinting. The techniques use the basics of 3D printing, in that cells and other biological materials are deposited in a layer-by-layer process to build three-dimensional biological structures.

Researchers have been studying the use of stem, muscle, and endothelial cells for bioprinting. One approach is to use these cells in a biocompatible “ink,” or bioink. These bioinks are typically water-based gels or hydrogels that help ensure the cells survive and even thrive through the process.

Now, let’s look at a few differences between bioprinting and 3D printing. Like 3D printing, a digital version of an organ or tissue is prepared. It is often based on an MRI or similar scan. Then this digital version is built in a layer-by-layer process. Then, other steps are taken to transform the build into something scientists can use. In some cases, these steps include chambers that help mature the built cell structure into a final usable organ or tissue.

Today, these structures are used for scientific research, for example to ascertain how certain chemicals will affect the organ or tissue. These 3D printed biological forms reduce animal testing, and help give scientists and researchers a better understanding of drug and chemical effects.

As of this writing there are several types of bioprinting.

With inkjet-based bioprinting, think of an office inkjet printer. Ink may be deposited through many tiny nozzles onto the build substrate. These bioprinters may be affordable, but they are limited to low-viscosity bioinks because higher viscosity materials will not flow through the nozzles.

Some bioprinters use a laser to precisely move cells from a solution onto the build surface. This technique enables the use of higher viscosity materials. Even though the laser enables precise positioning of cells, it can damage them due to the heat from the laser.

Similar to extrusion 3D printing, extrusion-based bioprinting forces the build material out of a nozzle. While this method offers more flexibility in usable materials, it may not place cells as precisely as desired.

Another option is to use a spraying or spinning technique to create droplets of build material. These options are known as electrospray and electrospinning bioprinters. Droplets can be nanometer in size. An issue is potential damage to the cells as these options often use high voltage.