An Energy Harvesting Underwater Acoustic Transmitter for Aquatic Animals

Wearable sensors for monitoring marine environments and their inhabitants

Human societies depend on marine ecosystems, but their degradation continues. Toward mitigating this decline, new and more effective ways to precisely measure the status and condition of marine environments are needed alongside existing rebuilding strategies. Here, we provide an overview of how sensors and wearable technology developed for humans could be adapted to improve marine monitoring. We describe barriers that have slowed the transition of this technology from land to sea, update on the developments in sensors to advance ocean observation and advocate for more widespread use of wearables on marine organisms in the wild and in aquaculture. We propose that large-scale use of wearables could facilitate the concept of an 'internet of marine life' that might contribute to a more robust and effective observation system for the oceans and commercial aquaculture operations. These observations may aid in rationalizing strategies toward conservation and restoration of marine communities and habitats.

Fish-Wearable Piezoelectric Nanogenerator for Dual-Modal Energy Scavenging from Fish-Tailing

Aiming to develop a self-powered bioelectric tag for fish behavioral studies, here we present a fish-wearable piezoelectric nanogenerator (FWPNG) that can simultaneously harvest the strain energy and the flow impact energy caused by fish-tailing. The FWPNG is fabricated by transferring a 2 μm-thick Nb0.02-Pb(Zr0.6Ti0.4)O3 (PZT) layer from a silicon substrate to a spin-coated polyimide film via a novel zinc oxide (ZnO) release process. The open-circuit voltage of the strain energy harvester reaches 2.3 V under a strain of 1% at an ultra-low frequency of 1 Hz, and output voltage of the impact energy harvester reaches a 0.3 V under a pressure of 82.6 kPa at 1 Hz, which is in good agreement with our theoretical analysis. As a proof-of-concept demonstration, an event-driven underwater acoustic transmitter is developed by utilizing the FWPNG as a trigger switch. Acoustic transmission occurs when the amplitude of fish-tailing is larger than a preset threshold. The dual-modal FWPNG device shows the potential application in self-powered biotags for animal behavioral studies and ocean explorations.

Towards breath sensors that are self-powered by design

Piezoelectric materials are widely used to generate electric charge from mechanical deformation or vice versa. These strategies are increasingly common in implantable medical devices, where sensing must be done on small scales. In the case of a flow rate sensor, a sensor's energy harvesting rate could be mapped to that flow rate, making it 'self-powered by design (SPD)'. Prior fluids-based SPD work has focused on turbulence-driven resonance and has been largely empirical. Here, we explore the possibility of sub-resonant SPD flow sensing in a human airway. We present a physical model of piezoelectric sensing/harvesting in the airway, which we validated with a benchtop experiment. Our work offers a model-based roadmap for implantable SPD sensing solutions. We also use the model to theorize a new form of SPD sensing that can detect broadband flow information.

An Atlas of Piezoelectric Energy Harvesters in Oceanic Applications

Nowadays, a large number of sensors are employed in the oceans to collect data for further analysis, which leads to a large number of demands for battery elimination in electronics due to the size reduction, environmental issues, and its laborious, pricy, and time-consuming recharge or replacement. Numerous methods for direct energy harvesting have been developed to power these low-power consumption sensors. Among all the developed harvesters, piezoelectric energy harvesters offer the most promise for eliminating batteries from future devices. These devices do not require maintenance, and they have compact and simple structures that can be attached to low-power devices to directly generate high-density power. In the present study, an atlas of 85 designs of piezoelectric energy harvesters in oceanic applications that have recently been reported in the state-of-the-art is provided. The atlas categorizes these designs based on their configurations, including cantilever beam, diaphragm, stacked, and cymbal configurations, and provides insightful information on their material, coupling modes, location, and power range. A set of unified schematics are drawn to show their working principles in this atlas. Moreover, all the concepts in the atlas are critically discussed in the body of this review. Different aspects of oceanic piezoelectric energy harvesters are also discussed in detail to address the challenges in the field and identify the research gaps.

A large dataset of detection and submeter-accurate 3-D trajectories of juvenile Chinook salmon

Acoustic telemetry has been used extensively to study the behavior of aquatic animals. The Juvenile Salmon Acoustic Telemetry System (JSATS) is one such system; it was developed for studying juvenile salmonids but has been used to study numerous species. A recent innovation of the JSATS system is an acoustic transmitter that is small enough to be implanted through injection or small incision that doesn’t require sutures. Use of the JSATS system involves deploying cabled acoustic receivers at hydroelectric dams, or other structures, and autonomous acoustic receivers in free-flowing sections of a river. The raw detections from acoustic-tagged fish are processed to remove potential false positives. The clean detections (5,147,996 total) are used to generate detection events and to compute 3-D trajectories (403,900 total), which are used to assign fish to a passage route through a dam. Controlled field testing involving a high-accuracy Global Positioning System receiver is done to validate the submeter accuracy of the trajectories. The JSATS dataset could be reused for expanding the understanding of near-dam fish behavior.

Measurement(s)	voluntary movement behavior • 3-D trajectory
Technology Type(s)	acoustic telemetry • Computation
Factor Type(s)	river • array type
Sample Characteristic - Organism	Oncorhynchus tshawytscha
Sample Characteristic - Environment	dam • freshwater biome
Sample Characteristic - Location	Little Goose Lock and Dam • Snake River • Columbia River • Lower Monumental Lock and Dam • McNary Dam • Bonneville Dam • Ice Harbor Lock and Dam • John Day Dam • Tucannon River

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.14939169

A Review of Energy Harvesting Techniques for Low Power Wide Area Networks (LPWANs)

The emergence of Internet of Things (IoT) architectures and applications has been the driver for a rapid growth in wireless technologies for the Machine-to-Machine domain. In this context, a crucial role is being played by the so-called Low Power Wide Area Networks (LPWANs), a bunch of transmission technologies developed to satisfy three main system requirements: low cost, wide transmission range, and low power consumption. This last requirement is especially crucial as IoT infrastructures should operate for long periods on limited quantities of energy: to cope with this limitation, energy harvesting is being applied every day more frequently, and several different techniques are being tested for LPWAN systems. The aim of this survey paper is to provide a detailed overview of the the existing LPWAN systems relying on energy harvesting for their powering. In this context, the different LPWAN technologies and protocols will be discussed and, for each technology, the applied energy harvesting techniques will be described as well as the architecture of the power management units when present.

A Review of PZT Patches Applications in Submerged Systems

Submerged systems are found in many engineering, biological, and medicinal applications. For such systems, due to the particular environmental conditions and working medium, the research on the mechanical and structural properties at every scale (from macroscopic to nanoscopic), and the control of the system dynamics and induced effects become very difficult tasks. For such purposes in submerged systems, piezoelectric patches (PZTp), which are light, small and economic, have been proved to be a very good solution. PZTp have been recently used as sensors/actuators for applications such as modal analysis, active sound and vibration control, energy harvesting and atomic force microscopes in submerged systems. As a consequence, in these applications, newly developed transducers based on PZTp have become the most used ones, which has improved the state of the art and methods used in these fields. This review paper carefully analyzes and summarizes these applications particularized to submerged structures and shows the most relevant results and findings, which have been obtained thanks to the use of PZTp.

Communicating through Touch: Macro Fiber Composites for Tactile Stimulation on the Abdomen

Research into sensory substitution systems has expanded, as alternative senses are utilized in real-time to afford object recognition or spatial understanding. Tactile stimulation has long shown promise as a communicatory strategy when applied unobtrusively to the redundant surface areas of the skin. Here, a novel belt, integrating a matrix of macro fiber composites, is purposed to deliver tactile stimuli to the abdomen. The design and development of the belt is presented and a systematic experimental study is conducted to analyze the impact of frequency and duty cycle. The belt is a beta precursor to a soft haptic feedback device that will enable situational awareness and obstacle avoidance through the localization of tactile stimulation relative to a body-centric frame of reference in a local environment.

Energy Harvesting Hybrid Acoustic-Optical Underwater Wireless Sensor Networks Localization

Underwater wireless technologies demand to transmit at higher data rate for ocean exploration. Currently, large coverage is achieved by acoustic sensor networks with low data rate, high cost, high latency, high power consumption, and negative impact on marine mammals. Meanwhile, optical communication for underwater networks has the advantage of the higher data rate albeit for limited communication distances. Moreover, energy consumption is another major problem for underwater sensor networks, due to limited battery power and difficulty in replacing or recharging the battery of a sensor node. The ultimate solution to this problem is to add energy harvesting capability to the acoustic-optical sensor nodes. Localization of underwater sensor networks is of utmost importance because the data collected from underwater sensor nodes is useful only if the location of the nodes is known. Therefore, a novel localization technique for energy harvesting hybrid acoustic-optical underwater wireless sensor networks (AO-UWSNs) is proposed. AO-UWSN employs optical communication for higher data rate at a short transmission distance and employs acoustic communication for low data rate and long transmission distance. A hybrid received signal strength (RSS) based localization technique is proposed to localize the nodes in AO-UWSNs. The proposed technique combines the noisy RSS based measurements from acoustic communication and optical communication and estimates the final locations of acoustic-optical sensor nodes. A weighted multiple observations paradigm is proposed for hybrid estimated distances to suppress the noisy observations and give more importance to the accurate observations. Furthermore, the closed form solution for Cramer-Rao lower bound (CRLB) is derived for localization accuracy of the proposed technique.

Rectifying the output of vibrational piezoelectric energy harvester using quantum dots

Piezoelectric energy harvester scavenges mechanical vibrations and generates electricity. Researchers have strived to optimize the electromechanical structures and to design necessary external power management circuits, aiming to deliver high power and rectified outputs ready for serving as batteries. Complex deformation of the mechanical structure results in charges with opposite polarities appearing on same surface, leading to current loss in the attached metal electrode. External power management circuits such as rectifiers comprise diodes that consume power and have undesirable forward bias. To address the above issues, we devise a novel integrated piezoelectric energy harvesting device that is structured by stacking a layer of quantum dots (QDs) and a layer of piezoelectric material. We find that the QD can rectify electrical charges generated from the piezoelectric material because of its adaptable conductance to the electrochemical potentials of both sides of the QDs layer, so that electrical current causing energy loss on the same surface of the piezoelectric material can be minimized. The QDs layer has the potential to replace external rectification circuits providing a much more compact and less power-consumption solution.