Hz Operation Research Articles

Eco-friendly, compact, and cost-efficient triboelectric nanogenerator for renewable energy harvesting and smart motion sensing

In recent years, the growth of Internet of Things devices has increased the use of sustainable energy sources. An alternative technology is offered by triboelectric nanogenerators (TENGs) that can harvest green energy and convert it into electrical energy. Herein, we assessed three different nopal powder types that were used as triboelectric layers of eco-friendly and sustainable TENGs for renewable energy harvesting from environmental vibrations and powering electronic devices. These nanogenerators were fabricated using waste and recycled materials with a compact design for easy transportation and collocation on non-homogeneous surfaces of different vibration or motion sources. In addition, these TENGs have advantages such as high output performance, stable output voltage, lightweight, low-cost materials, and a simple fabrication process. These nanogenerators use the contact-separation mode between two triboelectric layers to convert the vibration energy into electrical energy. TENG with the best output performance is based on dehydrated nopal powder, generating an output power density of 2.145 mWm−2 with a load resistance of 39.97 MΩ under 3g acceleration and 25 Hz operating frequency. The proposed TENGs have stable output voltages during 22500 operating cycles. These nanogenerators can light 116 ultra-bright blue commercial LEDs and power a digital calculator. Also, the TENGs can be used as a chess clock connected to a mobile phone app for smart motion sensing. These nanogenerators can harvest renewable vibration energy and power electronic devices, sensors, and smart motion sensing.

Prediction of Damping Ratio and Shear Modulus of Saturated Clay Soil under Rotating Machine

Developing countries' industrial growth necessitates innovative machine foundation design and resilient infrastructure. Meanwhile, soil properties play a significant role in the satisfactory design of machine foundations. The paper presents an experimental work to determine accurately the damping ratio and shear modulus by equations. The paper studies the effect of different parameters (embedded depth of foundation, shape of footing, and changing operating frequency of machine) on the damping ratio and shear modulus of saturated clay soil. Moreover, mathematical expressions are derived from statistical analysis to predict the damping ratio for rectangular and circular footing on saturated clay. The physical model results reveal that the damping ratio inside the soil will be increased with an increase in the depth of the point inside the soil for all cases. The damping ratio tends to decrease with an increase in operating frequency. The maximum damping ratio has occurred below a rectangular foundation with a 16.6 Hz operating frequency in saturated clay. The damping ratio is a function of many factors, such as embedment depth, degree of saturation, shape of foundation, and operation frequency of the machine.

Treadmill-based system for postural studies: Design and validation

Computer-controlled treadmills are common in many gait labs and offer great potential for conducting perturbation-based postural studies. However, the time-course of these disturbances can be too brief to be controlled manually through product software. Here we present a system that combines a Bertec® split-belt treadmill with custom hardware and software to deliver postural disturbances during standing and record data from multiple sources simultaneously. We used this system to administer to 15 healthy participants an 8-session perturbation-based training protocol in which they learned to respond without stepping to progressively larger perturbations. Kinematic, electromyographic, and force data were collected throughout. Motion capture was used to characterize the accuracy and repeatability of the treadmill-delivered perturbations with respect to duration, displacement, and peak velocity. These (observed) data were compared to that expected based on software commands and the known constraints of the treadmill (i.e., 10 Hz operating speed). We found perturbation durations to be as expected. Peak velocities and displacements were slightly higher than expected (average increases were 0.59 cm/s and 1.76 cm, respectively). Because this increase in magnitude was consistent, it did not impede training or affect data analysis. Treadmill behavior was repeatable across 95 % of trials.

High-performance magnetic thermal switch based on MnFe[formula omitted]O[formula omitted]/Ethylene Glycol:Water refrigerant dispersion

The use of magnetic nanoparticles for the remote control of heat transfer in electronic devices can overcome the current limitations of appliance engineering. In this work, we demonstrate that a thermal switch based on a low-cost and stable MnFe2O4/Ethylene Glycol:Water (MFO/EG:W) dispersion can increase the span temperatures as high as 60% in the 0.01–0.60 Hz operating frequency range under the same heat supply for different recipient filling ratios (FR). Under the optimum condition of FR = 80%, the efficiency of our new MFO/EG:W colloidal dispersion is twice the obtained for the commercial Fe3O4/paraffin oil fluid. From numerical calculation, we demonstrate that the improved heat exchange efficiency relates to the three-steps effective thermal conductivity variation during operation, expanding the contact time between the heat and cold sources. Thus, the combination of an EG:W refrigerant solution and superparamagnetic MFO nanoparticles with high saturation magnetization allows their use for heat management control of electronic systems for long operation periods.

On the flow unsteadiness and operational characteristics of a novel supersonic fluidic oscillator

A novel supersonic jet oscillating method is investigated both experimentally and numerically. A rectangular primary supersonic jet is issued into a confined chamber with sudden enlargement. Secondary control jets are issued from the top and bottom backward-facing step regions formed due to sudden enlargement. The primary jet is oscillated in the transverse direction by blowing the secondary jets in the streamwise direction in a pulsating manner with a phase shift. The out-of-phase secondary jet blowing causes the primary jet to periodically adhere to the upper and lower part of the confined chamber, causing flapping of the primary jet and acting as a supersonic fluidic oscillator. The supersonic jet oscillation characteristics are experimentally investigated using shadowgraph type flow visualization technique and steady and unsteady pressure measurements. Quantitative analysis of the shadowgraph images using the construction of y – t and y – f plots reveals the presence of periodic jet oscillation with a discrete dominant frequency similar to the secondary jet excitation frequency. The existence of linearity between the excitation frequency and the flapping jet frequency on the low-frequency (0.66–6.6 Hz) side is first proven experimentally. Later, the high-frequency (16.67–5000 Hz) operation extent of the supersonic fluidic oscillator is further demonstrated using unsteady computational studies owing to the existing experimental facility's limitations. A reduced-order analytical framework has also been proposed to investigate the limiting oscillation frequency. It is found that the limiting frequency predicted from the proposed analytical model shows fairly good agreement with the computationally predicted results (5 kHz).

An Eco-Friendly and Dual-Functional Ag@BMO-Chitosan-Based Triboelectric Nanogenerator for Self-Powered Gas Sensing Application

Real-time monitoring of hazardous gases is critical to determine the influence of the air environment on the lives of people. Herein, a highly biodegradable chitosan-based triboelectric gas sensor has been successfully fabricated by using Ag@Bi2MoO6-Chitosan (Ag@BMO-CS) bilayer film obtained with the facile drop-casting method, which paired with polydimethylsiloxane (PDMS) film as triboelectric layers. The output voltage of the 5% Ag-modified chitosan bilayer-based triboelectric nanogenerator reaches up to 8.35 V at 2 Hz operating frequency. The integrated self-powered gas sensor based on the triboelectrification and gas adsorption effects shows the ability to distinguish ammonia (NH3) gas sensitively, and the response to 20 ppm NH3 (ΔV/Va = 59.1%) is 1.4 times larger than the separated self-powered sensor. In addition, the sensing mechanism combining the triboelectric effect and gas-sensing reaction was proposed to demonstrate the enhancement of NH3 sensing performance for Ag@BMO-CS-based triboelectric gas sensors. This work presents a sustainable self-supply gas sensor based on TENG for the detection of NH3 gas without any external power supply, which has a broad spectrum of applications in hazardous gas leaks, non-invasive diagnostics and fresh food transportation.

Design of the Superconducting AC and DC Distribution for the ASCEND Demonstrator at Airbus

The ground-based Advanced Superconducting and Cryogenic Experimental power train Demonstrator (ASCEND) at Airbus intends to demonstrate the potential and feasibility of a cryogenic and superconducting powertrain as a breakthrough electric propulsion solution on future electric aircraft. A direct current distribution network is used in a propulsion chain to transfer 500 kW of power from the source to an electrical converter, which transforms the power into an alternating voltage/current to drive a superconducting motor. The working point of 1,700 A and 300 V is chosen for safety and installation reasons by operating at relatively low voltage. The direct current (DC) bus of ASCEND will be formed by a pair of high-temperature superconducting CORC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> cables inserted into a 10-meter-long narrow cryostat, resulting in a compact and lightweight solution. The 2-meter-long alternating current (AC) bus between the inverter and the electric motor is formed by a three-phase CORC <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">®</sup> cable. The challenge associated with 500 Hz operation in which a balance between AC loss in the cable and the size and mass of the system needs to be found, will be outlined. The AC and DC buses include several devices that connect the liquid nitrogen cooled power cables with the other system components that, in the case of the room temperature generator, operate at significantly higher temperatures. These devices thus include conduction-cooled current leads that are dimensioned to minimize the heat inleak from the warm to the cold environment. An overview of the design of the AC and DC buses and connecting devices will be provided and some of the design and operational challenges will be outlined.

A Highly Wearable Single-electrode Mode Triboelectric Nanogenerator Made of Flexible Polyvinylidene Fluoride Transparent Film for Muscular Motion Monitoring

The present study reports the design and fabrication of a single-electrode mode triboelectric nanogenerator (TENGs) which can overcome the drawbacks present in the conventional triboelectric nanogenerator which works on two electrodes and two dielectric layers. The proposed concept eliminates the dual electrodes thereby reducing the complexity of the device and the higher fabrication cost enabling the device to be used for extended applications. The fabricated TENG device uses Polyvinylidene fluoride (PVDF) as the active material that is capable to generate the electrical response upon contact with the human skin when the device was worn on the skin. The device generates the highest electrical output of ~ 50 V and a current of ~ 600 nA under a 1 Hz operating frequency. The device also shows good stability and durability by powering continuously for 300 s without any interruption in its electrical output response. The device shows its applicability in utilizing it powering low-power electronic devices, bio-mechanical energy scavenging upon actuated by hand and foot tapping, as well as demonstrated for the self-powered muscular monitoring system. The study greatly expands the opportunity of using TENGs for applications in the field of healthcare, bio-medical, and the Internet of Things (IoT).

Balancing performance of active magnetic regenerators: a comprehensive experimental study of aspect ratio, particle size, and operating conditions

Effective and, at the same time, efficient active magnetic regenerator (AMR) performance requires balanced geometry and operating conditions. Here the influence of regenerator shape, magnetocaloric material size, operating frequency, and utilization on the performance of gadolinium packed-particle bed AMRs is demonstrated experimentally. Various metrics are applied to assess effectiveness and efficiency. Observed temperature spans and cooling powers across a wide range of operating conditions are used to evaluate system performance and estimate exergetic cooling power and exergetic power quotient. A new metric combining exergetic cooling power and pump power provides an estimate of the maximum achievable second law efficiency. Five regenerator geometries with equal volumes and the aspect ratio from 1.0 to 3.8, and four different ranges of Gd spherical particles between 182 and 354 µm, are investigated. Improvements in system performance are demonstrated by a boost in specific cooling power of gadolinium from 0.85 to 1.16 W g−1 and maximum temperature span from 8.9 to 15.1 K. The optimum exergetic cooling power is observed for 1.37 utilization and 3 Hz operating frequency, exergetic power quotient exhibits a maximum at the same utilization but at 2 Hz frequency, while the highest efficiency is recorded at 1 Hz and utilization of 0.5, demonstrating that multiple performance metrics must be balanced to achieve regenerator design meeting all performance targets.

Triboelectric Nanogenerators (TENGs) Based on Various Flexible Polymeric Materials Along With Printed and Non-Printed Electrodes

Four designs (D1-D4) of flexible triboelectric nanogenerators (TENGs) were successfully fabricated in three different configurations for energy harvesting applications. Typically, TENG consists of anode layer, cathode layer, and electrodes. Combination of materials were investigated in this study using polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) and a flexible fabric as top triboelectric (cathode) layers; Kapton and polydimethylsiloxane (PDMS) as bottom triboelectric (anode) layers. Copper (Cu) tape and screen-printed silver (Ag) were used as electrodes. Each of these designs (D1-D4) has three configurations C1, C2 and C3 in which the top substrate (cathode layer) was different from one configuration to other. In order to determine the best material combination that would provide better TENG performance, different configurations were considered. The capability of the TENGs in terms of open circuit voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> ) and short circuit current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sc</sub> ) were demonstrated by subjecting them to ~5 to 6 N force at 10 Hz operating frequency. A maximum V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> of 21.61 ± 2.27 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , 35.32 ± 0.89 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> , 31.21 ± 1.43 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> and 45.75 ± 5.09 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> resulted in a power density of 0.29 μW/cm², 1.12 μW/cm², 0.47 μW/cm² and 0.91 μW/cm² from the D1, D2, D3 and D4 designs, respectively. The TENG fabricated using screen printed Ag flake on PDMS and fabric (D4) exhibited the highest open circuit output and a good repeatability after six months of re-testing with a maximum difference of ~ 7.39 % change(ΔV/V) in the output signal. In addition, a cyclic test was performed on D4, the results obtained demonstrate a good durability of the TENG sensor over 1000 cycles. The fabricated TENG device has a simple design, compact size, and demonstrated a better performance in comparison with some of the other works in terms of output voltage.

Transmission Line Voltage Calibration-Free Measurement Method

Voltage sensing technology is crucial in realizing distributed voltage sensing at critical nodes of the power grid and providing key state variables to provide information support for control decisions. Among the existing voltage measurement methods, voltage transformers have problems such as high insulation performance requirements and limited installation locations. However, non-contact voltage sensors designed based on the electric field coupling principle have sensor accuracy problems due to the instability of the coupling capacitance. Based on the above problems, this paper first proposes a floating ground measurement system based on an equipotential and differential structure. It also proposes a dual capacitance equivalent model for AC voltage measurement on transmission lines. Based on this method, a calibration method for the amplitude and phase of the sensor is built. Under the voltage test at 50 Hz operating frequency in the voltage range (100–300 V), the maximum relative error of the voltage amplitude is 0.89%, and the maximum relative error of the voltage phase is 0.68°. The maximum relative error of voltage amplitude under a 50 Hz operating frequency voltage test in the voltage range (600 V–10 kV) is 4.48%. In the final scenario adaptation analysis, the method’s specific height amplitude accuracy error was experimentally verified to be 0.88%, with a maximum difference of 0.52% for multi-type conductor testing.

3D-Printed High-Frequency Dielectric Elastomer Actuator toward Insect-Scale Ultrafast Soft Robot

Insects with small and light bodies possess the capability of agile and fast movement in a small space. Inspired by nature, an insect-like soft robot may update the strategies in many scenarios like exploration, rescue, etc. However, the design and mass manufacture of soft robots combining insect size, fast mobility, good robustness, and impact-perception capability still present great engineering challenges. Herein, we report an insect-scale (15 mm body length (BL), 450 mg body weight) and ultrafast (∼4.0 BL s–1) soft robot. The remarkable motion performance is attributed to the high-frequency (760 Hz) operation as well as the long lifetime (>one million cycles) of its artificial muscle, which is a coil dielectric elastomer actuator (DEA) made by multimaterial coaxial three-dimensional printing with well-designed highly elastic materials and 5-inlets nozzle structure. The current robot is not only the smallest and fastest among the reported DEA-driven robots but also obtains high robustness, good environmental adaptability, and impact-perception capability: It can run on various grounds and complex paths, climb inside small pipes, work in robot swarms, and sustain and perceive the impact of the external environment.

The new high field septum magnet for upgrading of fast extraction in main ring of J-PARC

The upgrade of the beam power of J-PARC Main Ring to 750 kW by reducing the cycle from 2.48 s to 1.3 s is underway, and the upgrade of the four high-field (HF) septa will be completed by summer of 2023. The operation test of one HF septum, SM31, was conducted in 2020. First trial was 1 Hz operation test, and we confirmed the joule heating at the magnetic coil was lower than limit. Second was magnetic field measurement. We obtained a good linearity between the applied current and the gap field without saturation. The field integral of the gap field was measured to estimate the optimal current for beam extraction, and we found it is 3,400 A. We compared the gap field between in the neutrino line and that in the beam abort line, then we found the longitudinal distributions have a small discrepancy but it was acceptable. The large leakage field was observed around the end-fringes, therefore, in order to reduce the leakage field, we produced an additional duct shield for mounting in the circulating duct in 2022. We verified that the additional duct shield reduced the leakage field to ≈2% of unshielded leakage field. The new SM31 and other two HF septa have been installed in MR by end of May 2022. The beam operation with the new HF septa will be started in June 2022.

Performance Study on a Soft X-ray Betatron Radiation Source Realized in the Self-Injection Regime of Laser-Plasma Wakefield Acceleration

We present an analysis of the performance of a broadband secondary radiation source based on a high-gradient laser-plasma wakefield electron accelerator. In more detail, we report studies of compact and ultra-short X-ray generation via betatron oscillations in plasma channels. For the specific working point examined in this paper, determined by the needs of other experiments ongoing at the facility, at ∼0.02 Hz operation rate, we have found ≲106 photons emitted per shot (with a fluctuation of 50%) in the soft X-rays, corresponding to a critical energy of ∼0.8 keV (with a fluctuation of 40%). The source will be implemented for experiments in time-domain spectroscopy, e.g., biological specimens, and for other applications oriented to medical physics.

Design and Characteristic Analysis of Magnetostrictive Vibration Harvester with Double-Stage Rhombus Amplification Mechanism

Vibration energy harvesting is a new alternative to lithium battery power for low-power devices, attempting to recover wasted or lost vibration energy to generate electricity. Magnetostrictive-based energy harvesting exploits the coupling properties of the Villari and Faraday electromagnetic induction effects to achieve mechanical–magnetic–electric energy conversion. In order to better apply to the actual vibration environment, such as buses, and improve the ability to capture low-frequency vibration energy, a double-stage rhombus vibration energy harvesting device, based on Terfenol-D rods, was developed. By establishing an analytical model of the force amplification ratio of the harvesting device, the design is optimized using the Single-Objective Genetic Algorithm, and the safety and pre-magnetization layout methods are analyzed by Finite Element Analysis. The output characteristics of the prototype, including the output voltage frequency response under low-frequency regular excitation and random excitation, the effect of external resistance, and the vibration energy capture performance under random excitation, are investigated in detail through experiments. The results of the experiments showed that the peak output power of the fabricated prototype was 1.056 mW at 30 Hz operating frequency, the energy harvesting capability reached 41.4 μW/N, and the peak open circuit voltage and output power were 2.92 V and 266 mW, respectively, under random excitation. Practical application test results showed that the peak voltage generated was 1.06–1.51 V when the excitation level was 2.2–4.9 m/s2. The comparative study indicates that the output performance of the proposed double-stage rhombus magnetostrictive vibration energy harvesting system is a great improvement over the proposals of existing literature.

Muscle-Inspired Linear Actuators by Electrochemical Oxidation of Liquid Metal Bridges.

Progress in artificial muscles relies on new architectures that combine soft matter with transduction mechanisms for converting controlled stimuli into mechanical work. Liquid metal, in particular eutectic gallium–indium (EGaIn), is promising for creating an artificial muscle since it is intrinsically deformable and capable of generating significant force and shape change through low voltage stimulation. In this work, a muscle‐inspired structure for designing liquid metal actuators is presented, where EGaIn droplets are configured with copper pads to linearly contract. By theory and experiments, it is demonstrated that this design enables higher work densities and stress, making it a favorable actuator at smaller length scales. Furthermore, higher frequency (up to 5 Hz) operation is achieved by prestretching an antagonistic pair of actuators, where energy bistability enables fast‐switching actuation. Overall, this muscle‐inspired architecture shows a unique combination of low voltage operation, higher energy density at smaller scales, structural scalability, and higher frequency actuation.

Single-shot experiments at the soft X-FEL FERMI using a back-side-illuminated scientific CMOS detector.

The latest Complementary Metal Oxide Semiconductor (CMOS) 2D sensors now rival the performance of state-of-the-art photon detectors for optical application, combining a high-frame-rate speed with a wide dynamic range. While the advent of high-repetition-rate hard X-ray free-electron lasers (FELs) has boosted the development of complex large-area fast CCD detectors in the extreme ultraviolet (EUV) and soft X-ray domains, scientists lacked such high-performance 2D detectors, principally due to the very poor efficiency limited by the sensor processing. Recently, a new generation of large back-side-illuminated scientific CMOS sensors (CMOS-BSI) has been developed and commercialized. One of these cost-efficient and competitive sensors, the GSENSE400BSI, has been implemented and characterized, and the proof of concept has been carried out at a synchrotron or laser-based X-ray source. In this article, we explore the feasibility of single-shot ultra-fast experiments at FEL sources operating in theEUV/soft X-ray regime with an AXIS-SXR camera equipped with the GSENSE400BSI-TVISB sensor. We illustrate the detector capabilities by performing a soft X-ray magnetic scattering experiment at the DiProi end-station of the FERMI FEL. These measurements show the possibility of integrating this camera for collecting single-shot images at the 50 Hz operation mode of FERMI with a cropped image size of 700× 700 pixels. The efficiency of the sensor at a working photon energy of 58 eV and the linearity over the large FEL intensity have been verified. Moreover, on-the-fly time-resolved single-shot X-ray resonant magnetic scattering imaging from prototype Co/Pt multilayer films has been carried out with a time collection gain of 30 compared to the classical start-and-stop acquisition method performed with the conventional CCD-BSI detector available at the end-station.

Core size effects of laser fusion subcritical research reactor for fusion engineering research

A multi-purpose high repetition laser facility, the so-called Japan establishment for power-laser community harvest (J-EPoCH) is proposed as a next generation laser facility. J-EPoCH will operate at the maximum rate of 100 Hz. The omnidirectional 12 laser beams with 8 kJ would yield ∼1013 neutrons with a large high aspect ratio target. As one of the applications of J-EPoCH, a laser fusion subcritical research reactor has been conceptually designed based on existing technologies. Moreover, a variety of fusion engineering studies: energy conversion, tritium breeding, neutron irradiation effects, etc, can be conducted. The feasibility of the subcritical research reactor is considered in terms of neutron-thermal (n-t) conversion and tritium breeding. Lead–lithium alloy (Li17Pb83) and boron carbide (B4C) have the potential to be studied for preliminary fusion power generation. The subcritical reactor will generate 21.4 W and 20.0 W of the thermal fusion power with the Li17Pb83 and the B4C layers of the thickness of 80 cm, respectively at 1 Hz operation. The Li17Pb83 layer of a 5 mm thickness will achieve the temperature rise of 0.203 mK per shot. The thermal fusion energy is detectable with conventional measurement techniques. The core with the Li17Pb83 layer thickness of 100 cm will yield more than one tritium from a deuterium–tritium fusion neutron. However, laser windows reduce the efficiency of n-t conversion and tritium yield.

10 J operation of a conductive-cooled Yb:YAG active-mirror amplifier and prospects for 100 Hz operation.

We report, to the best of our knowledge, the highest power conductive-cooled active-mirror amplifier (CcAMA) using Yb:YAG with a pulse energy of 10 J. By using four liquid-nitrogen circulating cooled laser heads, we achieved a repetition rate, pulse energy, and average power of 33.3 Hz, 9.3 J, and 310 W, respectively. The problem of wavefront distortion, which is difficult to solve with a large-aperture active-mirror laser, is suppressed by using reinforcing materials with the same thermal expansion coefficient. We have confirmed that the wavefront distortion is small (0.15λ P-V per head) at 100 Hz operation, which paves the way for 100 Hz operation with the CcAMA concept.

Ring-Embedded Micro-Power mm-Sized Optical Sensor for Accurate Heart Beat Monitoring

This paper presents a wearable optical health monitoring device embedding a monolithic sensor chip with newly designed pixels, and an optical module optimized for photoplethysmography (PPG). The monolithic optical sensor at the heart of this device implements an array of novel pixels designed specifically for PPG and featuring a quantum efficiency (QE) as high as 85 %. The sensor readout chain, as well as the logic circuits, implements low power design techniques leading to only 60μA current consumption at 122 Hz operation frequency, including digital communication. Thanks to the high QE and optical module optimization, medical grade PPG recordings are enabled with less than 10μA emitter current. The optical sensor is embedded in an ergonomic ring device together with system electronics in order to enable in-field test of beat detection accuracy on 7 subjects. The ring device detects correctly 97.87% of the beats on a total of 72.21 hours of recording. The inter-beat interval (IBI) estimation from these recordings features a mean absolute error (MAE) as low as 8.10 ms. This performance is achieved with less than 70μA current consumption at the level of the PPG module.