Reverse electrowetting-on-dielectric (REWOD) human energy harvester towards hybridisation with piezoelectricity for self-powered wearable biosensors

Piezoelectric beam generator based on MFC as a self-powered vibration sensor

Herein we introduce a novel water-based graphite ink modified with multiwalled carbon nanotubes, designed for the development of the first wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis. The stencil-printed graphite (SPG) electrodes, printed onto a flexible substrate, were modified by casting multiwalled carbon nanotubes (MWCNTs), electrodepositing polymethylene blue (pMB) at the anode to serve as a catalyst for nicotinamide adenine dinucleotide (NADH) oxidation, and hemin at the cathode as a selective catalyst for H2O2 reduction. Notably, alcohol dehydrogenase (ADH) was additionally physisorbed onto the anodic electrode, and alcohol oxidase (AOx) onto the cathodic electrode. The self-powered biosensor was assembled using the ADH/pMB-MWCNTs/SPG||AOx/Hemin-MWCNTs/SPG configuration, enabling the detection of ethanol as an analytical target, both at the anodic and cathodic electrodes. Its performance was assessed by measuring polarization curves with gradually increasing ethanol concentrations ranging from 0 to 50 mM. The biosensor demonstrated a linear detection range from 0.01 to 0.3 mM, with a detection limit (LOD) of 3 ± 1 µM and a sensitivity of 64 ± 2 μW mM−1, with a correlation coefficient of 0.98 (RSD 8.1%, n = 10 electrode pairs). It exhibited robust operational stability (over 2800 s with continuous ethanol turnover) and excellent storage stability (approximately 93% of initial signal retained after 90 days). Finally, the biosensor array was integrated into a wristband and successfully evaluated for continuous alcohol abuse monitoring. This proposed system displays promising attributes for use as a flexible and wearable biosensor employing biocompatible water-based inks, offering potential applications in forensic contexts.Graphical A novel water-based graphite ink modified with multiwalled carbon nanotubes designed for the development of a wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis.

Structural health monitoring is widely used for maintaining and monitoring various structures in different areas. In general, the structural health monitoring system life span depends on the capability of the batteries, but it can be increased by energy harvesting approaches to autonomously produce power. These autonomously powered structural health monitoring systems have received increasing attention over the past decades. This article reviews recent developments in the ambient energy sources and energy harvesting methods for structural health monitoring applications. First, the earliest and most common method of harvesting energy from sunlight and wind is discussed. Then, vibration and thermal gradient energy harvesting methods are reviewed together with their feasibilities. Finally, radio frequency energy harvesting, a unique method developed in recent years, is highlighted. A double-resonant coil ferrite rod antenna for radio frequency energy harvesting in medium frequency band is proposed. Simulation results indicate that the proposed double-resonant coil ferrite rod antenna can increase the gain by 2.8 dBi and the receiving voltage by 25.77% compared with a conventional single-resonant coil ferrite rod antenna.

Hybrid Energy-Harvesting Systems Based on Triboelectric Nanogenerators

Self-powered and wearable biosensors for healthcare

Introduction and Aim: Wearable biosensors represent a new era in digital health and biotechnology, offering non-invasive, continuous, and real-time monitoring of physiological and biochemical parameters. This review discusses their classification, applications, technological development, and future potential in disease prediction and personalized medicine. Materials and Methods: Relevant literature on past, present, and emerging wearable biosensors was analyzed, covering sensor types, operational principles, connectivity (wired and wireless), and integration with advanced technologies such as artificial intelligence (AI), cloud computing, and next-generation wireless communication. Sources were selected based on their relevance to real-time health monitoring and disease prediction. Results: Wearable biosensors are broadly divided into biophysiological sensors, which measure parameters such as heart rate, temperature, and motion, and biochemical sensors, which detect bioanalytes in biological fluids like sweat, saliva, and interstitial fluid. Major applications include blood glucose monitoring, cardiovascular assessment, pulmonary function tracking, and evaluation of mental health and sleep patterns. The combination of AI, cloud systems, and wireless networks enhances diagnostic precision and predictive accuracy. Market reports project the wearable biosensor industry to surpass USD 60 billion by 2030, with an annual growth rate exceeding 12, indicating expanding research and adoption. Conclusion: Wearable biosensors are transforming healthcare by enabling proactive, personalized, and remote medical management. Despite challenges in biocompatibility, stability, data security, and regulation, advances in flexible materials, energy-efficient designs, and AI-based systems continue to drive their evolution and clinical integration.

Energy harvesting from transportation infrastructures has garnered more attention over the past few years. Owning to the severe climate change and depletion of non-renewable resources, it has become pertinent to devise and implement sustainable energy harvesting methods. One of the most energy abundant yet least utilized areas to harvest energy are roads within the transportation infrastructure. There are three common energy forms that energy harvesting methods would rely upon. They are solar energy, thermal energy, and mechanical energy. The objective of this paper is to conduct a comparative analysis of energy harvesting methods of these three common energy forms within the transportation infrastructure. Each harvesting methodology is compared in terms of applicability, energy source, energy production, challenges, and future use. This study was performed through a review of literature and case studies relating to the respective energy harvesting methods. The research showed current applicability of solar energy harvesting within the transportation infrastructure provides the most benefits in terms of energy production, viability, and maintainability. Currently, research for solar energy harvesting, in general, has significantly outpaced that of thermal energy and mechanical energy harvesting. However, with more research and technological improvements, mechanical energy harvesting has the capability to become the largest energy harvesting method within the transportation infrastructure. This is because the transportation infrastructure is heavily influenced by mechanical loads from vehicles. Overall, more research and testing are needed to solidify these energy harvesting methods and to use them regularly as a renewable energy source within the transportation infrastructure.

Flexible and wearable biosensors have received tremendous attention over the past decade owing to their great potential applications in the field of health and medicine. Wearable biosensors serve as an ideal platform for real-time and continuous health monitoring, which exhibit unique properties such as self-powered, lightweight, low cost, high flexibility, detection convenience, and great conformability. This review introduces the recent research progress in wearable biosensors. First of all, the biological fluids often detected by wearable biosensors are proposed. Then, the existing micro-nanofabrication technologies and basic characteristics of wearable biosensors are summarized. Then, their application manners and information processing are also highlighted in the paper. Massive cutting-edge research examples are introduced such as wearable physiological pressure sensors, wearable sweat sensors, and wearable self-powered biosensors. As a significant content, the detection mechanism of these sensors was detailed with examples to help readers understand this area. Finally, the current challenges and future perspectives are proposed to push this research area forward and expand practical applications in the future.

The human body is a source of multiple types of energy, such as mechanical, thermal and biochemical, which can be scavenged through appropriate technological means. Mechanical vibrations originating from contraction and expansion of the radial artery represent a reliable source of displacement to be picked up and exploited by a harvester. The continuous monitoring of physiological biomarkers is an essential part of the timely and accurate diagnosis of a disease with subsequent medical treatment, and wearable biosensors are increasingly utilized for biomedical data acquisition of important biomarkers. However, they rely on batteries and their replacement introduces a discontinuity in measured signals, which could be critical for the patients and also causes discomfort. In the present work, the research into a novel 3D-printed wearable energy harvesting platform for scavenging energy from arterial pulsations via a piezoelectric material is described. An elastic thermoplastic polyurethane (TPU) film, which forms an air chamber between the skin and the piezoelectric disc electrode, was introduced to provide better adsorption to the skin, prevent damage to the piezoelectric disc and electrically isolate components in the platform from the human body. Computational fluid dynamics in the framework of COMSOL Multiphysics 6.1 software was employed to perform a series of coupled time-varying simulations of the interaction among a number of associated physical phenomena. The mathematical model of the harvester was investigated computationally, and quantification of the output energy and power parameters was used for comparisons. A prototype wearable platform enclosure was designed and manufactured using fused filament fabrication (FFF). The influence of the piezoelectric disc material and its diameter on the electrical output were studied and various geometrical parameters of the enclosure and the TPU film were optimized based on theoretical and empirical data. Physiological data, such as interdependency between the harvester skin fit and voltage output, were obtained.

The energy harvesting is the branch of the energy management, where the energy is being originated from the multiple sources. The energy harvesting is usually done from the sources such as wind mills, solar cells, piezoelectric and other similar power generation modules. In this paper, the energy harvesting methods are discussed for the wireless sensor networks. The wireless sensor networks are the networks consisted of the small sensor devices and used to collect the various kinds of data such as environmental pressure, temperature, rain measure, air quality, forest or building fire monitoring, humidity, etc. In this model, energy harvesting setup focuses upon the controlled release of the energy required to run the basic operations on each sensor device. The energy estimation is performed to estimate the amount of energy. Maximum power point tracking(MPPT)is utilized to obtain the maximum power output from the source of the energy. The basic operation based energy calculation and request operation based energy estimation method is combined to estimate the energy for the WSN operations. The overhead energy is utilized to charge the backup battery, the stored power of battery can be utilized in the working failure spans originated by the absence or failure of power source. The proposed approach is aimed at gaining the maximum benefit from the energy harvesting model to facilitate the continuous WSN operations. In this paper various MPPT algorithms are compared, analyzed and finally tabulated to get maximum insight.

Recently, many researcher was studied on energy harvesting. There are two environments of energy harvester namely outdoor activities and indoor activities. The indoor sources can be obtained from plant microbial fuel cells, vibration energy from machine, and radio frequency energy or electromagnetic energy from telecommunications signal. This paper is interested in vibration energy. One of the material that can convert mechanical energy ie vibration to electrical energy is piezoelectric material. Piezoelectric material can convert stress i.e vibration into charge i.e electrical energy. This paper is proposed an interdigitated electrodes (IDE) pattern with unimoprh piezoelectric cantilever generator (PCG) with flame retardant 4 (FR4) for energy harvesting device. PVDF is used as piezoelectric material. The characterization of IDE with different finger length and width are discussed. The PVDF is used as sensing element and targeted to increase the displacement because of their flexibility. Three designs have been developed in difference sizes of electrode finger width, 0.5mm, 1.0mm and 2.0mm with the same gap between electrode finger, 0.5mm. The experiments were characterized the pressure effect to energy harvester, the vibration effect to energy harvester and frequency of tap on energy harvester effect to energy storage. The results are show that the size of finger width 2.0 mm will produce more energy compare to 0.5 mm and 1.0 mm. The electrode finger width 2.0 mm is used as an energy harvesting device and did the experiment of energy harvest stored in capacitor.

There have been a constant demand of diagnostics devices due to growing aging population and rising chronic diseases. An urge to improve the current healthcare infrastructure has been driving the growth of wearable biosensors. Wearable bio sensors are the devices attached to the human body that detect and monitor changes in body vital parameters. Technology innovations in high integration, energy harvesting, wireless power transfer, advanced materials, printed, flexible and organic devices are playing an important role in the development of wearable biosensors. Also market penetration of smartphones and smart watches is an important factor for driving global market of wearable biosensors. This paper reviews recent developments in wearable biosensors and presents current challenges in wearable biosensor development. Further emerging trends with the advancements in technology have been presented which may accelerate the development of wearable biosensor in near future.

Sound pollution has been capturing more and more attention around the world. Piezoelectric materials convert acoustic energy into electrical energy and actively attenuate the sound simultaneously. In this paper, an electro-spun nonwoven polyvinylidene difluoride nanofiber membrane as a high-performance piezoelectric material is found to have an ultra-high acoustoelectric conversion capability at the low sound frequency range. The novelty of the material in this paper is the proposed electro-spun piezoelectric nano-fiber web, which presents a strong acoustic-to-electric conversion performance. The piezoelectric acoustic energy harvester consists of the polyvinylidene difluoride nanofiber membrane that vibrates under the sound wave excitation. The piezoelectric acoustic energy harvester device can precisely detect the sound of 72.5 Hz with a sensitivity as high as 711.3 mV Pa-1 which is higher than the sensitivity of a commercial piezoelectric poly (vinylidene fluoride) membrane device. The energy harvesting performance of the piezoelectric acoustic energy harvester device is simulated by the comsol software and then validated with the experimental results to illustrate its excellent energy harvesting ability. Based on the validated simulation model, a regression parameter model is developed from the comsol software simulation results using the response surface method. The empirical regression parameter model is applied to predict the energy harvesting performance of the acoustic energy harvester from input design parameters or material property parameters where the sensitivity of the design parameters or material property parameters and their interactions can be analyzed. The design or material property parameters can be optimized for the best energy harvesting performance based on the regression parameter model. The optimization results show a significant improvement in the energy harvesting performance. The sensitivity of the parameters on the energy harvesting performance also indicates the potential of the large-scale application of this acoustic energy harvester.

Analysis of compressive sensing and energy harvesting for wireless multimedia sensor networks

This paper proposes an advanced design concept for a piezoelectric energy harvesting (EH) device, multimodal EH skin structure, a thin and compact harvester which can generate power from multimodal vibration. Multimodal EH skin is an extended study of our previous works, EH skin, which is a new conceptual design for piezoelectric energy harvester by combining a vibrating skin structure and an additional thin piezoelectric layer into one embodiment. A computational (FE) model for the EH skin’s multilayers – a vibrating skin structure and a piezoelectric layer – is constructed and the optimal topology and shape of the piezoelectric layer is found for maximum power generation from multiple vibration modes. For finding topological distribution, the piezoelectric material is segmented along inflection lines from multiple vibration modes of interests in order to minimize voltage cancellation. A case study taken from an outdoor unit skin proves the excellent performance of multimodal EH skin by showing larger power generation rather than an EH skin without segmentation or a unimodal EH skin. The presented design concept can be easily applied to any engineering system with harmonic-vibrating skins.