3-D Printed Membrane Holds Sensors Close to Heart

Elastic membranes shaped precisely to match the epicardium of an individual's heart have been created by Igor Efimov, PhD, school of engineering and applied science, Washington University (St. Louis), and a team of researchers via the use of 3-D printing.

Current technology cannot cover the full surface of the epicardium, or maintain reliable contact for continual use without sutures or adhesives, so Efimov and his team turned to 3-D printing to create a fully conformable 3-D structure that may be implanted.

The membrane forms an integumentary device that completely envelops the heart in a form-fitting manner. It can be employed as a platform for deformable arrays of multifunctional sensors, electronic, and optoelectronic components. Examples of such devices include actuators for electrical, thermal, and optical stimulation, and sensors for pH, temperature and mechanical strain.

A paper describing this work was published online in the journal Nature Communications on February 25.

Efimov, who is the Lucy & Stanley Lopata Distinguished Professor of Biomedical Engineering, spoke with Beth Miller of the Washington University Newsroom. "With this application, we image the patient's heart through MRI or CT scan, then computationally extract the image to build a 3-D model that we can print on a 3-D printer," he said. "We then mold the shape of the membrane that will constitute the base of the device deployed on the surface of the heart."

Since the silicon material forming the membrane has inherent elasticity it provides a mechanically stable biotic/abiotic interface during normal cardiac cycles. The attached components can be semiconductor materials such as silicon, gallium arsenide and gallium nitride.

Coleader of the team is John Rogers, PhD, director of the F. Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign. Rogers developed the semiconductor sensors, which can be co-integrated with metals, metal oxides, and polymers to provide operational capabilities.

But the heart is not the only organ for which this technology may be useful. Efimov continued, "Because this is implantable, it will allow physicians to monitor vital functions in different organs and intervene when necessary to provide therapy. In the case of heart rhythm disorders, it could be used to stimulate cardiac muscle or the brain, or in renal disorders, it would monitor ionic concentrations of calcium, potassium and sodium."

The membrane could even hold a sensor to measure troponin, a protein expressed in heart cells and a hallmark of a heart attack. Troponin analysis is the standard of care for a patient suspected of having had a heart attack. Ultimately, Efimov says, such devices will be combined with ventricular assist devices.

This method of detecting a heart attack differs from research at Scripps Health that aims to predict a heart attack by analyzing the levels of endothelial cells in the blood stream.

Stephen Levy is a contributor to Qmed and MPMN.