By E&T editorial staff

Northwestern University researchers have developed a wireless pacemaker that integrates into a network of four soft, flexible, wireless, wearable sensors and control units placed around the upper body which can harmlessly dissolve when no longer needed.

The sensors communicate with each other to continuously monitor the body’s various physiological functions, including body temperature, oxygen levels, respiration, muscle tone, physical activity and the heart’s electrical activity.

The system then uses algorithms to analyse this combined activity in order to autonomously detect abnormal cardiac rhythms and decide when to pace the heart and at what rate. All this information is streamed to a smartphone or tablet, so physicians can remotely monitor their patients.

The new transient pacemaker and sensor/control network can be used in patients who need temporary pacing after cardiac surgery or are waiting for a permanent pacemaker.

The pacemaker wirelessly harvests energy from a node within the network - a small wireless device that adheres to the patient’s chest. The technology eliminates the need for external hardware, including wires.

To enable the system to communicate with the patient, the researchers incorporated a small, wearable haptic-feedback device that can be worn anywhere on the body. When the sensors detect an issue (such as low battery power, incorrect device placement or pacemaker malfunction), the haptic device vibrates in specific patterns that alert wearers and inform them of the problem.

“This marks the first time we have paired soft, wearable electronics with transient electronic platforms,” said lead researcher John A. Rogers.

“This approach could change the way patients receive care providing multinodal, closed-loop control over essential physiological processes – through a wireless network of sensors and stimulators that operates in a manner inspired by the complex, biological feedback loops that control behaviours in living organisms.

“For temporary cardiac pacing, the system untethers patients from monitoring and stimulation apparatuses that keep them confined to a hospital setting.

“Instead, patients could recover in the comfort of their own homes while maintaining the peace of mind that comes with being remotely monitored by their physicians. This also would reduce the cost of health care and free up hospital beds for other patients.”

Today’s temporary pacemakers typically require a wire that is connected to an external generator that stimulates the heart. When the heart regains its ability to stimulate itself appropriately, the wire has to be pulled out in an operation.

“We created a pacemaker that simply dissolves and does not need to be removed,” researcher Igor R. Efimov said. “This avoids the dangerous step of pulling out the wire.”

The 'body-area network' includes a battery-free pacemaker to temporarily pace the heart; a cardiac module that sits on the chest to provide power, sense electrical activity and the sounds of the heart, and a hemodynamics module that sits on the forehead to take various body diagnostics.

“We wanted to demonstrate that it’s possible to deploy multiple different types of devices, each performing essential functions in a wirelessly coordinated manner across the body,” Rogers said.

“Some are sensing. Some are delivering power. Some are stimulating. Some are providing control signals. But they all work together, trading information, making decisions based on algorithms and reacting to changing conditions.

“The vision of multiple bioelectronic devices all talking to one another and performing different functions at different relevant anatomical locations is a frontier area that we will continue to pursue going into the future.”

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