Self-powered Cardiovascular Electronic Devices And Systems
REVIEWSSelf-powered cardiovascular electronicdevices and systemsQiang Zheng1,2, Qizhu Tang3, Zhong Lin Wang1,4 and Zhou Li1,2 Abstract Cardiovascular electronic devices have enormous benefits for health and quality of lifebut the long-term operation of these implantable and wearable devices remains a huge challengeowing to the limited life of batteries, which increases the risk of device failure and causesuncertainty among patients. A possible approach to overcoming the challenge of limited batterylife is to harvest energy from the body and its ambient environment, including biomechanical,solar, thermal and biochemical energy, so that the devices can be self-powered. This strategycould allow the development of advanced features for cardiovascular electronic devices, suchas extended life, miniaturization to improve comfort and conformability, and functions thatintegrate with real-time data transmission, mobile data processing and smart power utilization.In this Review, we present an update on self-powered cardiovascular implantable electronicdevices and wearable active sensors. We summarize the existing self-powered technologies andtheir fundamental features. We then review the current applications of self-powered electronicdevices in the cardiovascular field, which have two main goals. The first is to harvest energy fromthe body as a sustainable power source for cardiovascular electronic devices, such as cardiacpacemakers. The second is to use self-powered devices with low power consumption and highperformance as active sensors to monitor physiological signals (for example, for active endocardialmonitoring). Finally, we present the current challenges and future perspectives for the field.1CAS Center for Excellencein Nanoscience, Beijing KeyLaboratory of Micro-NanoEnergy and Sensor, BeijingInstitute of Nanoenergyand Nanosystems, ChineseAcademy of Sciences,Beijing, China.2School of Nanoscience andTechnology, University ofChinese Academy of Sciences,Beijing, China.3Department of Cardiology,Renmin Hospital of WuhanUniversity, Wuhan, China.4School of Materials Scienceand Engineering, GeorgiaInstitute of Technology,Atlanta, GA, USA. e-mail: 0.1038/s41569-020-0426-4Cardiovascular diseases are the primary cause of deathglobally1. The WHO estimated that 17.9 million peo ple died from cardiovascular diseases in 2016 and thatthis number will increase to 23.6 million by 2030 (ref.2).Of these deaths, 85% are caused by myocardial infarc tion or stroke2. In these patients, early diagnosis andtimely intervention are of great importance for survival.In the past 50 years, the emergence of cardio vascularelectronic devices (CEDs), such as implantable pace makers, implantable cardioverter–defibrillators (ICDs),cardiac resynchronization therapy devices and vari ous implantable or wearable monitoring devices, hasbeen hugely beneficial to cardiovascular health andhas reduced morbidity and mortality associated withcardiovascular disease3. CEDs have evolved and arenow smaller, with a longer battery life and improvedfunctionality compared with previous devices. However,some limitations curtail the greater uptake andwidespread application of this technology, mostlyassociated with finite battery life, miniaturization,sensing capacities, lead malfunction and device-relatedinfections. In this Review, we discuss the next gene ration of CEDs, which involve self-powered tech nology4 and which are designed to address some ofthe main limitations in the field. We also summarizeNature Reviews Cardiologythe prospects in the near future for implantable andwearable ‘intelligent’ CEDs.Current technologies for CEDsImplantable CEDsIn 1958, the first implantable pacemaker was developed5and, since then, tremendous improvements in cardiovas cular implantable electronic devices (CIEDs) have beenmade. Modern CIEDs, including implantable pacemak ers,ICDs, cardiac resynchronization therapy devices,implantable loop recorders and implantable haemody namic monitoring devices, have already saved millionsof lives by providing more accurate and continuousdiagnostic and therapeutic capability (Fig. 1). The growth,general ageing and increasing life expectancy of theworldwide population have resulted in increased pre valence of chronic diseases, such as heart failure and atrialfibrillation, meaning that CIEDs have an increasinglyimportant role in modern health-care systems.Cardiac pacemakers. Cardiac pacemakers are the bestknown and most widely used CIEDs and were initiallyused to correct electrical conduction disorders, such asbradycardia and syncope6. Each year, millions of patientsundergo permanent implantation of a pacemaker to
ReviewsKey points The introduction of implantable or wearable electronic devices has revolutionizeddiagnosis and therapy in cardiovascular medicine, reducing morbidity and mortalityof millions for patients with cardiovascular disease. Current battery-powered cardiovascular electronic devices have a limited life anddo not allow long-term, uninterrupted monitoring or treatment of cardiovasculardisease, which is crucial for preventing death and/or improving quality of life. Abundant sources of energy exist in the human body and the surroundingenvironment, such as biomechanical, solar, thermal and biochemical energy. Self-powered technology, which converts energy from the human body or surroundingenvironment into electricity, can provide a sustainable source of power to replace orsupplement battery technology.prevent or treat life-threatening cardiac conditions. Thedesign of pacemakers has continually evolved, reflect ing both technological progress and increasing under standing of cardiac function. Today, pacemakers havethe typical single-chamber and dual-chamber modes,as well as more advanced pacing methods, such asbiventricular pacing (also known as cardiac resynchro nization therapy7–10) and His-bundle pacing11,12. Thesenew pacing modes require complex sensing capacities,alternative functions and improvements in system opti mization, such as battery longevity, miniaturization,leadless design and software upgrades. For example,optimized software algorithms can iteratively test thepacing threshold and automatically adjust the outputpower, thereby prolonging the life of the pacemaker to atotal of 10 years13,14. Other algorithms can be used tomonitor atrioventricular nodal conduction and optimizepacing in patients with intermittent atrioventricularnode block15,16.Implantable cardioverter–defibrillators. ICDs areanother class of battery-powered CIED, commonlyused for preventing sudden cardiac death in patientswith known, sustained ventricular tachycardia or fibril lation. Studies have shown that ICDs can have a role inpreventing cardiac arrest in individuals who have nothad, but are at high risk of developing, life-threateningventricular arrhythmias17,18. ICDs can also have the fea tures of a pacemaker. New devices provide additional‘overdrive’ pacing to electrically convert a sustainedventricular tachycardia or ‘back-up’ pacing if brady cardia occurs. ICDs also offer a host of other sophisti cated functions, such as the abilities to record detectedarrhythmic events and to perform electrophysiologicaltesting19. Modern ICDs have a volume of 40 cm3, sim ilar to that of older-generation pacemakers. However,the life of ICDs (approximately 5 years) is shorter thanthat of pacemakers (approximately 12.5 years) becausetheir continuous working mode requires greater powerconsumption. Therefore, extending the battery life ofICDs is a priority.Implantable loop recorders. Implantable loop record ers are a type of CIED used for heart monitoring.Implantable loop recorders can record an individual’sheart rhythm continuously for 3 years, providing arange of important information that cannot be obtainedby other methods, which can assist with making adefinite diagnosis and instituting effective treatment.For example, implantable loop recorders can cap ture infrequently occurring abnormal heart rhythmsthat are missed by standard electrocardiography ordynamic electrocardiography from a Holter monitor20.Implantable loop recorders are often used to diagnosearrhythmia-based syncope, which is difficult by otherapproaches21. Implantable loop recorders are also usedto detect recurrences of atrial fibrillation or tachycardiaafter ablation procedures22,23. Battery life is also a majorconcern with this type of device.Wearable or portable CEDsWearable electronic devices have revolutionized dig ital and mobile health monitoring by enabling healthmonitoring to be continuous and longitudinal, bothwithin and outside the clinical setting24. In cardiovas cular medicine, wearable electronic devices have anextremely broad range of potential applications in ena bling the monitoring of vital signals to help to diagnoseboth acute and chronic forms of cardiovascular dis ease. Cardiovascular wearable electronic devices can bedivided into four main categories on the basis of theirfunction: electrocardiography and heart rhythm moni tors, heart rate monitors, haemodynamic monitors25 anddaily activity monitors. Cardiovascular wearable elec tronic devices come in various designs, including wristbands (cuffs)26,27, smart watches28–31, rings32, vests33, chestpatches34–36 and T-shirts37 (Fig. 1).Wearable electrocardiography and heart rhythm monitors. As early as the 1960s, “evanescent cardiac abnor malities and phantom arrhythmias” were being detectedwith the use of ambulatory electrocardiography toexplain clinical syndromes38. With the development ofcost-effective mobile communication technology, ambu latory electrocardiography signals could be recorded anddata uploaded remotely via the mobile cardiac outpatienttelemetry system developed in 2002 (ref.25). Currently,smaller and more convenient wearable devices forrecording electrocardiographic data have been approvedfor use, including the KardiaBand (AliveCor), AppleWatch (Apple) and ScanWatch (Withings). These devicescan detect atrial fibrillation and classify heart rhythmas being normal or out-of-range in just a few seconds,providing clinicians with valuable diagnostic data.Wearable heart rate monitors. Various wearable elec tronic devices for continuous, real-time heart rate mon itoring have been developed. These wearable deviceshave evolved from chest-strap monitors to wristbandmonitors. The measurement of heart rate has advancedfrom the traditional, simple recordings taken by physi cians to the continuous, daily monitoring taken by indi viduals wearing these devices. The most commonly usedtechnology in wearable devices for the detection of heartrate is photoplethysmography, which measures changesin light absorbance through the skin39,40 and has an errorof 10%41,42. However, these measurements might be lessaccurate during exercise or in individuals with dark skinpigmentation, tattoos or high levels of body fat.www.nature.com/nrcardio
Reviews1 SAN4 PFCardiacconductionsystem2 AVNAbnormal conduction Impulse generation failure Impulse propagation block Abnormal pathway3 HisCardiac disease Heart failure Arrhythmias Bradycardia TachycardiaCardiac signal monitoring and conduction system interventionWearable electronicdevicesImplantableelectronic devicesChest strapECG, temperatureVagal nerve stimulationHeart failureChest patchAcoustic, HR, ECG,temperaturePacemakerBradycardiaConduction disturbanceSmart vest torHeart failure, arrhythmiaWristband and smartwatch and ringECG, HR, BP, SpO2,temperatureCardiacresynchronization therapyHeart failure12Implantable loop recorderContinuous ECG34Implantablehaemodynamic monitoringContinuous PAPFig. 1 Existing electronic devices for cardiac conduction disease. The cardiac impulse originates in the sinoatrial node(SAN) and moves through the atrioventricular node (AVN), the His bundle (His), and the left and right bundle branches,and stimulates their terminal Purkinje fibres (PF). These structures (1–4) are identified in the image of the heart. Abnormalconduction of electrical signals in this pathway can cause a variety of cardiovascular diseases. Therefore, monitoring ofcardiac signals and timely interventions targeting the conduction system are crucial. Cardiovascular electronic deviceshave been developed for the diagnosis and treatment of cardiac conduction disease. Existing devices can be dividedinto two classes: wearable electronic devices, mainly for monitoring cardiac-related signals, including chest straps andpatches, smart vests and T-shirts, wristbands, and smart watches and rings; and implantable electronic devices, includingvagal nerve stimulation devices, pacemakers, implantable cardioverter–defibrillators, cardiac resynchronization therapydevices, implantable loop recorders and implantable haemodynamic monitoring devices. BP, blood pressure; ECG,electrocardiogram; HR, heart rate; PAP, positive airway pressure; SpO2, blood oxygen saturation.Wearable haemodynamic monitors. Given the increas ing prevalence of heart failure, tools that can detectearly signs of decompensation are greatly needed43,44.Wearable devices for remote dielectric sensing and bio impedance monitoring were developed for this purposeand can identify differences in the dielectric properties ofdifferent tissues to provide a quantitative analysisof the degree of pulmonary congestion and the levels ofintrathoracic fluid45. The use of wearable bioimpedancemonitors to detect transthoracic impedance is moreconvenient and sensitive than current clinical methodsfor predicting heart failure such as gain in body mass,which can also reflect the intrathoracic impedance andintrathoracic fluid level46.Wearable daily activity monitors. Daily activity data can beused to support cardiovascular clinical decision-making.These data can be used to predict the risk of cardiovascu lar disease and to help patients with chronic cardiovas cular disease to make timely alterations to their therapeuticregimen. Activity monitors are usually mechanical motionNature Reviews Cardiologysensors that rely on accelerometers to measure movement.The accelerometer can be integrated with other weara ble equipment to record estimates of applied forces, bodymotions and the surrounding environment. However,several problems still constrain the widespread use ofwearable daily activity monitors in clinical practice47, andfurther validation is needed. For example, accelerometersare not suitable for assessing non-ambulatory activities,and the limited life of batteries makes the continuous useof wearable monitors a challenge48.Considerations for next-generation CEDsThe fundamental motivation for the invention ofimplantable and wearable CEDs was to free patientsfrom the time and space constraints of repeatedmeasurements in a health-care setting and to providelong-term, uninterrupted monitoring and treatment.To achieve these aims, a CED must have a sustainableenergy supply and integrated functionality.With current battery technologies, CEDs needto be replaced or recharged periodically, depending
ReviewsPiezoelectric effectThe capacity of certainmaterials to generate anelectrical charge in responseto applied mechanical force.CrystalA solid material whoseconstituents (such as atoms,molecules and ions) arearranged in a highly orderedmicroscopic structure to forma crystal lattice that extendsin all directions.Electric dipole momentThe separation of a positivecharge and a negative chargeby a distance; a measure ofthe polarity of a system.Wurtzite structureA hexagonal crystal structurethat occurs in various binarycompounds; named after themineral wurtzite.C-axisIn crystal drawings, byconvention, the c-axis isusually oriented verticallyin the plane of the paper;all crystals except those witha cubic (or isometric) crystalstructure have a c-axis.Charge centreThe position in a chargedistribution with non-zerototal charge where the electricdipole moment vanishes.SuperpositionSuperposition is the capacityof a quantum system to bein multiple states at the sametime until it is measured.TriboelectrificationA type of contact electrificationwhereby certain materialsbecome electrically chargedafter they are separated froma different material with whichthey were in contact.Electrostatic inductionA method to create orgenerate static electricityin a material by bringing anelectrically charged objectnear to it, which causes theelectrical charges to beredistributed in the material,resulting in one side havingan excess of either positiveor negative charges.on utilization and battery volume. Developments inimplantable devices over the past two decades haveled to a reduction in the volume of ICDs from 70 cm3to 30 cm3 and an extension in their life from 5 years to10 years49. However, many patients still require replace ment of their CED because of limited battery capacity aswell as issues related to chemistry and physical structure(size and mass). Furthermore, physicians need to balancethe life expectancy of the patient and the life of the CEDbecause a mismatch can increase the likelihood of needingto change the CED, which is associated with a fourfoldincreased risk of infection and up to a fivefold increasedrisk of lead complications50,51. For rechargeable wearabledevices, limited battery capacity greatly constrains patientfreedom when using the device and reduces compliance.Conversely, to meet the extensive requirements forclinical approval, future CEDs will require more func tions, more powerful computing and remote communi cation capabilities, which will further increase the powerconsumption of the device. For example, the meanmaximum predicted life of existing single-chamberand dual-chamber pacemakers is 12.0 2.1 years and9.8 1.9 years, respectively (calculated using data on thesix latest mainstream models of pacemaker) (Table 1).If more advanced features were incorporated, such asremote monitoring, pre-arrhythmia electrocardiogramstorage and rate response, the life of devices would bereduced by approximately 0.5–3.6 years51. On the basis ofthese considerations, alternative energy sources, such astriboelectric nanogenerators (TENGs) and piezoelectricnanogenerators (PENGs), solar energy harvesters,thermal energy harvesters and biofuel cells, are currentlybeing assessed in preclinical studies (Fig. 2a). These strat egies, which convert energy from the human body or itssurrounding environment into electricity to provide asustainable power source, can be defined as self-poweredtechnologies. These technologies can potentially be usedto design the next generation of CEDs.Existing self-powered technologiesTechnologies to harvest energy to power CEDs sus tainably are urgently needed. However, the energysources available in biological systems are mainly theslow stretching of muscle, the slow flow of biofluidsand blood, and possibly infrared light and sonic wavesthat can penetrate deep tissues. Biomechanical action isone of the major sources of power and has attracted alot of attention. The following technologies have beendeveloped to capture these energy sources (Table 2).Piezoelectric nanogeneratorsThe piezoelectric effect is a way of generating an internalelectric potential by applying a mechanical force52,53.Typically, when an external force is applied to a piezoelec tric material, mutual displacement of anions and cationsoccurs in the crystal and produces an electric dipole moment.Cumulatively, this process generates a difference inthe potential distribution throughout the material in thedirection of the tension. PENGs, or piezoelectric genera tors when referring to non-nanomaterial systems, wereinvented using nanomaterials or bulk materials with apiezoelectric effect, including some inorganic materials,such as zinc oxide (ZnO), lead zirconate titanate (PZT),barium titanate, modified PZT, lead metaniobate, lead bar ium niobate and modified lead titanate, and some organicmaterials, su
Wearable electronic devices have revolutionized dig ital and mobile health monitoring by enabling health monitoring to be continuous and longitudinal, both within and outside the clinical setting24. In cardiovas cular medicine, wearable electronic devices have an extremely broad range of potential applications in ena
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implanted electronic devices If a person with a pacemaker or ICD has return of spontaneous circulation after receiving CPR, the device should be interrogated and checked (usually by a cardiac devices physiologist) at the earliest opportunity. 1.4 After death (see section 16) If a person with a cardiovascular implanted electronic device suffers
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The Pecolift / Ecolift 1.5 (referred to as "the machine" in this manual) is a simple, safe and efficient alternative to step-ladders, platform/podium steps and small scaffold towers. It is the first non-powered, powered access platform. It does not require batteries (or charging) or connection to an electricity supply.
teaching 1, and Royal Colleges noting a reduction in the anatomy knowledge base of applicants, this is clearly an area of concern. Indeed, there was a 7‐fold increase in the number of medical claims made due to deficiencies in anatomy knowledge between 1995 and 2007.
