Sheath with Several Sensors Can Replace Pacemakers

A biomedical engineering research team led by John Rogers from the University of Illinois at Urbana-Champaign recently developed a tailor-made silicon membrane which acts as a sheath enclosing a still-beating rabbit heart. This membrane functions as a monitor of different aspects of cardiac activity including the heart’s electrical activity, mechanical strain, temperature, and pH.

Rogers and the rest of the research team have previously developed removable skin patches which act as sensors. This time around, what they did was to first reproduce a high quality replica of a rabbit’s heart through 3D printing. Several ultra-thin components and ribbon-like cables were then mounted on the surface of the heart model. After which, a thin layer of silicon elastomer was applied. The finished product is a flexible, 3D membrane with actuators and sensors strategically placed in a cloak-like fashion.

The membrane is produced in a smaller size than heart. Rogers explained that this property of the device is important in that good contact with the surface is obtained since the membrane needs to be stretched to fit the heart.

The researchers have also tested the membrane on a still-beating heart of a rabbit enclosed in a perfusion chamber. The sheath device showed no significant interference with the pumping function of the heart. Through biomedical science research, it has also been able to show promising results compared to the conventional laboratory based monitoring equipment. The device was able to successfully measure heart rhythm as well as real time pH changes.

This new device is proposed to replace implantable defibrillators and pacemakers currently being used in the medical practice. The researchers said that the device is superior to sensitivity when determining cardiac activity.

Cardiac pH is an important determinant of the probability of sudden cardiac arrest. It is an indicator of reduced blood flow to the heart, which is often followed by heart attack. Efimov pointed out that the presence of pH sensors on the device also adds to its functionality as a cardiac sensor. He says that the membranes can be used to predict sudden cardiac arrest due to its pH sensing capability, although it’s too early to tell as the device is on its early stages.

Although the sheath-like cardiac sensor has a great potential, it is yet to be tested in live environment. Rogers explained that several factors should still be taken into consideration including the effect of the membrane on the adjacent tissues and structures while fitting the sheath over the heart. It is hard to tell, Rogers says, until the device is tested in vivo.

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