Origami Helps Implant Sensors in Bio-Printed Tissue

In the United States alone, more than 100,000 people currently need a lifesaving organ transplant. Instead of waiting for donors, one way to solve this crisis in the future is to assemble replacement organs with bio-printing—3D printing that uses inks containing living cells. Scientists in Israel have found that origami techniques could help fold sensors into bio-printed materials to help determine whether they are behaving safely and properly.

Although bio-printing something as complex as a human organ is still a distant possibility, there are a host of near-term applications for the technique. For example, in drug research, scientists can bio-print living, three-dimensional tissues with which to examine the effects of various compounds.

Ideally, researchers would like to embed sensors within bio-printed items to keep track of how well they are behaving. However, the three-dimensional nature of bio-printed objects makes it difficult to lodge sensors within them in a way that can monitor every part of the structures.

“It will, hopefully in the future, allow us to monitor and assess 3D biostructures before we would like to transplant them.” —Ben Maoz, Tel Aviv University

Now scientists have developed a 3D platform inspired by origami that can help embed sensors in bio-printed objects in precise locations. “It will, hopefully in the future, allow us to monitor and assess 3D biostructures before we would like to transplant them,” says Ben Maoz, a professor of biomedical engineering at Tel Aviv University in Israel.

The new platform is a silicone rubber device that can fold around a bio-printed structure. The prototype holds a commercial array of 3D electrodes to capture electrical signals. It also possesses other electrodes that can measure electrical resistance, which can reveal how permeable cells are to various medications. A custom 3D software model can tailor the design of the origami and all the electrodes so that the sensors can be placed in specific locations in the bio-printed object.

The scientists tested their device on bio-printed clumps of brain cells. The research team also grew a layer of cells onto the origami that mimicked the blood-brain barrier, a cell layer that protects the brain from undesirable substances that the body’s blood might be carrying. By folding this combination of origami and cells onto the bio-printed structures, Maoz and his colleagues were able to monitor neural activity within the brain cells and see how their synthetic blood-brain barrier might interfere with medications intended to treat brain diseases.

Maoz says the new device can incorporate many types of sensors beyond electrodes, such as temperature or acidity sensors. It can also incorporate flowing liquid to supply oxygen and nutrients to cells, the researchers note.

Currently, this device “will mainly be used for research and not for clinical use,” Maoz says. Still, it could “significantly contribute to drug development—assessing drugs that are relevant to the brain.”

The researchers say they can use their origami device with any type of 3D tissue. For example, Maoz says they can use it on bio-printed structures made from patient cells “to help with personalized medicine and drug development.”

The origami platform could also help embed devices that can modify bio-printed objects. For instance, many artificially grown tissues function better if they are placed under the kinds of physical stresses they might normally experience within the body, and the origami platform could integrate gadgets that can exert such mechanical forces on bio-printed structures. “This can assist in accelerating tissue maturation, which might be relevant to clinical applications,” Maoz says.

The scientists detailed their findings in the 26 June issue of Advanced Science.