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Posted on November 11, 2016 by  & 

Self-powered, flexible and one-stop implantable triboelectric sensor

The use of implantable electronic devices is largely reliant on the lifetime of batteries, which have to be replaced periodically by surgical procedures once exhausted, causing physical and mental suffering to patients and increasing healthcare cost. Besides efficiently scavenging the mechanical energy of internal organs, a group of scientists in China are proposing a self-powered, flexible and one-stop implantable triboelectric active sensor (iTEAS) that can provide continuous monitoring of multiple physiological and pathological signs.
As demonstrated in human-scale animals, the device can monitor heart rates, reaching an accuracy of ~99%. Cardiac arrhythmias such as atrial fibrillation and ventricular premature contraction can be detected in real-time. Further, a novel method of monitoring respiratory rates and phases is established by analyzing variations of the output peaks of the iTEAS. Blood pressure can be independently estimated and the velocity of blood flow be calculated with aid of a separate arterial pressure catheter. With the core-shell packaging strategy of the proposed device, monitoring functionality remains excellent during 72 hours after closure of the chest. The in vivo biocompatibility of the device is examined after 2 weeks of implantation, proving suitability for practical use. As a multifunctional biomedical monitor which is exempt from external power supply, the proposed iTEAS holds great potential in future healthcare industry.
Recently, a broad spectrum of investigations emerged that focused on harvesting mechanical energy in living environments to replace batteries. The flexible iTEAS is implanted into the pericardial sac of living swine and fixed to the pericardium. In responding to the heartbeat and breathing, an electric output with an open-circuitvoltage (VOC) of∼10 V and a short-circuit current (ISC) of∼4μA can be yielded, showing a robust self-generated capability and removing the need for an onboard battery. The integration of nanostructured triboelectric layers and pliable encapsulating materials enable the proposed biomedical sensor to detect tiny changes of motions of circumferential organs.
Source and top image: Nano Letters
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