Motion Detection Sensors Research Articles

Multi-Dimensionally Functionalized Pressure Sensor for Human Motion Detection Based on 1D AgNWs/2D rGO-Coated 3D Porous Sponge

Multi-Dimensionally Functionalized Pressure Sensor for Human Motion Detection Based on 1D AgNWs/2D rGO-Coated 3D Porous Sponge

Fabrication of TPU-Supported Au-Bi2S3/Ti3C2Tx electrospun mat: Towards flexible and Multi-functional sensors for human motion and NH3 detection at room temperature

The potential applications of wearable sensors in health monitoring, micro-environment detection, and advanced soft electronic noses have attracted widespread attention. However, due to the inherent limitations of traditional organic flexible substrates, simultaneously achieving excellent flexibility, high sensitivity, robustness, and breathability remains a significant challenge. Herein, using the electrospinning method, a flexible TPU substrate film was prepared, and Bi2S3/Ti3C2Tx nanocomposite materials were synthesized through a simple one-step hydrothermal method. Au nanoparticles were attached to the surface of the composite material using sodium borohydride, and finally, the surface impregnation method was used to successfully prepare the Au-Bi2S3/Ti3C2Tx-TPU flexible electrospun mat. The as-prepared sensor demonstrated an outstanding response of 154 % to 100 ppm NH3 at room temperature, coupled with high selectivity, repeatability, and long-term stability. The strain properties of the sensor were also evaluated, showcasing its potential for human motion and physiological feature detection, such as breathing, swallowing, and limb movements. The study’s findings indicated that the Au-Bi2S3/Ti3C2Tx-TPU electrospun mat sensor has promising applications in flexible electronics, wearable environmental monitoring devices, and human healthy monitoring.

Implementation of the Internet of Things in Centrifuge Calibrators

The implementation of Internet of Things (IoT) technology in centrifuge calibrators brings innovation by enhancing accuracy and efficiency in medical device calibration. This research develops an IoT-based centrifuge calibrator capable of storing calibration data digitally and providing real-time access, using the E18-D80NK sensor for rotational motion detection, which is more cost-effective than conventional laser modules. Measurement results demonstrate high accuracy across various RPM settings (1000, 1500, 2000, 2500, and 3000 RPM), with minimal error and stability within acceptable tolerance limits. The key advantage of IoT implementation lies in efficient calibration data management, enabling real-time access and integration with other systems for effective analysis and monitoring of calibration outcomes. Overall, IoT technology in centrifuge calibration not only enhances healthcare service quality with reliable results but also supports efficient and transparent equipment management in medical settings, offering long-term benefits to healthcare facilities and patients.

MXene-based self-adhesive, ultrasensitive, highly tough flexible hydrogel pressure sensors for motion monitoring and robotic tactile sensing

With the rapid development of artificial intelligence and human–computer interaction fields, wearable electronic devices represented by flexible pressure sensors have a wider range of application scenarios. In this paper, we used a composite hydrogel made by one-pot polymerization using a combination of acrylamide (AM), sodium carboxymethyl cellulose (CMC), dopamine (DA), and MXene (Ti3C2Tx). The composite hydrogel has the advantages of self-adhesion, high sensitivity, large detection range (0–500 kPa), low detection limit, high toughness (compression > 90 %), stability (more than 6700 s) and other advantages of hydrogel flexible pressure strain sensor. Sodium carboxymethyl cellulose (CMC), as a multifunctional thickener and gelling agent, significantly improves rheological properties and viscosity in hydrogels, forms crosslinked structures to enhance mechanical properties and provides reliable toughness for pressure sensors. Dopamine (DA), which is rich in catechol groups, can adhere to the material surface through oxidative polymerization to enhance bond strength. Hydrogel pressure sensors for human motion detection can accurately track joint movement, respond sensitively to changes in knocks and touches, and display specific characters such as Morse code. The technology extends to robotic systems, where pressure-activated electrical signals are used to control robot movements. Therefore, it has a very promising application in the field of human–computer interaction, human-body movement signal detection, etc. PAM/CMC/DA/MXene hydrogel pressure sensors have excellent mechanical, electrical, and adhesion properties, which provide a more reliable solution for the fields of flexible wearable e-skin, human–computer interaction, and tactile sensing.

Cost-Efficient Automated Intrusion Detection and Reporting System for Homes in Nigeria

Substantial investments are made to mitigate the persistent threat to lives and assets posed by various forms of intrusion. Automated security systems have emerged as crucial tools for safeguarding homes against intrusions in recent times. A major advantage of this is its independent ability to report human activities around homes without direct observation. However, the cost of implementing the system is not pocket-friendly to an average Nigerian given the prevailing economic situation. This research therefore seeks to develop and implement an intrusion detection and reporting system using low cost materials while maintaining a balance between quality and cost at the same time. The system architecture employs the passive infrared sensor (PIR) for motion detection, the ultrasonic sensor measures intruders’ location from the home entrance while the NodeMCU ESP8266 microcontroller is responsible for coordinating the reception and relaying of signals within the system. The system was implemented with varying distances of human presence from the security device. Reports of potential intrusion alerts were obtained within reasonable time frames (between 11 seconds and 49 seconds) on the homeowner’s mobile phone via the Blynk application. This performance demonstrates the reliability of the system for home security. The system is equally cost-efficient relative to most similar state-of-the art IoT based home security systems considered in this work. Our work therefore contributes to knowledge by proposing an affordable home security solution for a low budget Nigerian user.

Porous reduced graphene oxide@multi-walled carbon nanotubes/polydimethylsiloxane piezoresistive pressure sensor for human motion detection

With the rapid development of wearable electronic, smart robot and health monitoring, there is a growing focus on flexible piezoresistive pressure sensors. Herein, a new strategy is proposed to prepare flexible piezoresistive pressure sensor with porous polydimethylsiloxane (PDMS) sponge as matrix and reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) for the construction of dual-conductive network. The sensor exhibited excellent overall sensing performances (pressure detection range of 0–200 kPa, sensitivity of 1.62 kPa−1 in 0–29 kPa and 0.41 kPa−1 in 29–65 kPa, response/recovery time of 61/40 ms and 22,000 loading-unloading cycles at 0–15 % compressive strain). Meanwhile, the sensor was able to normally work in the range of 30–100 °C and affected little by temperature. In addition, the sensor was successfully applied for detecting various human motions as well as music recognition and identification. The piezoresistive pressure sensor has great application prospect in wearable devices, health monitoring, and human-machine interaction.

Ultra-stretchable and adhesive hydrogel based on double network structure as flexible strain sensor for human motion detection

In recent years, conductive hydrogels were widely applied as flexible strain sensor due to its outstanding stretchability, high flexibility and conductivity. However, most conductive hydrogels would reduce the sensitivity and accuracy of hydrogel-based strain sensor for the lack of self-adhesion. Herein, a highly stretchable and excellent adhesive hydrogel based on chitosan network and ionic liquid crosslinking network was prepared. Chitosan (CS) worked as network skeleton, which could enhance the mechanical properties of hydrogel by participating in the construction of double network structure. Furthermore, dimethylaminoethyl methacrylate maleate (DM-M) as cross-linker, the hydrogel was imparted with high ionic conductivity (0.29 S/m) while it also enhanced the mechanical properties of the hydrogel. The ionic bonding conferred high toughness to the hydrogel for avoiding stress concentration during tensile process. Additionally, the hydrogel could form strong adhesion to a variety of substrate surfaces through electrostatic interaction, hydrogen bond and metal complexation. Meanwhile, the hydrogel remained strong adhesion under different pH, solvent and temperature condition. Therefore, the hydrogel with excellent adhesive property, mechanical properties and high electrical conductivity have been designed as flexible strain sensor, which could detect limb movement and physiological signals with real-time feedback electrical signals. Thus, this highly stretchable, tough and adhesive hydrogel based on double network structure would promote the development of flexible electronic device.

Integrating High-Performance Flexible Wires with Strain Sensors for Wearable Human Motion Detection.

Flexible electronics have revolutionized the field by overcoming the rigid limitations of traditional devices, offering superior flexibility and adaptability. Conductive ink performance is crucial, directly impacting the stability of flexible electronics. While metal filler-based inks exhibit excellent conductivity, they often lack mechanical stability. To address this challenge, we present a novel conductive ink utilizing a ternary composite filler system: liquid metal and two micron-sized silver morphologies (particles and flakes). We systematically investigated the influence of filler type, mass ratio, and sintering process parameters on the composite ink's conductivity and mechanical stability. Our results demonstrate that flexible wires fabricated with the liquid metal/micron silver particle/micron silver flake composite filler exhibit remarkable conductivity and exceptional bending stability. Interestingly, increasing the liquid metal content results in a trade-off, compromising conductivity while enhancing mechanical performance. After enduring 5000 bending cycles, the resistance change in wires formulated with a 4:1 mass ratio of micron silver particles to flakes is only half that of wires with a 1:1 ratio. This study further investigates the mechanism governing resistance variations during flexible wire bending. Additionally, we observed a positive correlation between sintering temperature and pressure with the conductivity of flexible wires. The significance of the sintering parameters on conductivity follows a descending order: sintering temperature, sintering pressure, and sintering time. Finally, we demonstrate the practical application of this technology by integrating the composite ink-based flexible wires with conductive polymer-based strain sensors. This combination successfully achieved the detection of human movements, including finger and wrist bending.

Highly Stretchable, Conductive, Adhesive, and Self-Powered Ionogel Sensor for Human Motion Detection, Signal Transmission, and Traffic Monitoring

Highly Stretchable, Conductive, Adhesive, and Self-Powered Ionogel Sensor for Human Motion Detection, Signal Transmission, and Traffic Monitoring

Vertically Aligned Laser-Patterned Carbon Nanotube-Based Strain-Less Sensor for Motion Detection

Vertically Aligned Laser-Patterned Carbon Nanotube-Based Strain-Less Sensor for Motion Detection

Developing a residential occupancy schedule generator based on smart thermostat data

Occupancy patterns play a major role in residential buildings’ energy demand. This role is essential to be represented realistically in urban-scale energy simulations with a focus on matching the supply of renewable energy to demand. However, the lack of large-scale datasets that represent the seasonality and dynamic nature of occupancy, especially within the residential sector limited such analysis. Recently, the fast adoption of smart thermostats, featuring passive infrared sensors for motion detection, in residential buildings has allowed for extracting more representative occupancy information for different applications. To this end, this study introduces an open-source Python package to generate large-scale hourly occupancy profiles for residential buildings based on smart thermostat readings. The package takes advantage of the Donate Your Data (DYD) dataset by Ecobee to develop a rule-based framework that addresses the limitations of relying on motion-detection data to represent the whole-building occupancy. The framework was applied to over 8000 Canadian households as a case study. The generated profiles for these buildings are validated by comparing them with residential occupancy profiles generated from the Canadian Time Use Survey (TUS). The results showed that both profiles were statistically similar with a 3 % difference in the aggregated daily occupied hours. Finally, the diversity of the generated profiles before and after the COVID-19 pandemic is investigated to demonstrate the usefulness of the tool. The results proved the potential of the developed package to generate realistic and diverse occupancy schedules for the residential sector.

Silver Nanowire-Based Flexible Strain Sensor for Human Motion Detection.

Accurately capturing human movements is a crucial element of health status monitoring and a necessary precondition for realizing future virtual reality/augmented reality applications. Flexible motion sensors with exceptional sensitivity are capable of detecting physical activities by converting them into resistance fluctuations. Silver nanowires (AgNWs) have become a preferred choice for the development of various types of sensors due to their outstanding electrical conductivity, transparency, and flexibility within polymer composites. Herein, we present the design and fabrication of a flexible strain sensor based on silver nanowires. Suitable substrate materials were selected, and the sensor's sensitivity and fatigue properties were characterized and tested, with the sensor maintaining reliability after 5000 deformation cycles. Different sensors were prepared by controlling the concentration of silver nanowires to achieve the collection of motion signals from various parts of the human body. Additionally, we explored potential applications of these sensors in fields such as health monitoring and virtual reality. In summary, this work integrated the acquisition of different human motion signals, demonstrating great potential for future multifunctional wearable electronic devices.

All-Textile Piezoelectric Nanogenerator Based on 3D Knitted Fabric Electrode for Wearable Applications.

Flexible, air permeable and elastic self-powered sensors for human motion monitoring and assisted medical rehabilitation have recently become a hot research topic. However, most current piezoelectric sensors can not account for many characteristics. Addressing this challenge, an all-textile piezoelectric sensor (ATPS) based on 3D structured knitted fabric electrodes is reported. The ATPS consists of a piezoelectric element polyvinylidene fluoride nanofiber membrane, flexible knitted fabric electrodes, and an elastic self-adhesive bandage. Based on the flexible and efficient knitting technology, the sensor has the advantages of low cost, flexibility, simple structure, and convenient large-area manufacturing. Experimental and finite element simulation results show that the knitting pattern of fabric electrodes can enhance the piezoelectric output of ATPS. The optimal ATPS has a high voltage response sensitivity of up to 0.68 V/kPa. The proposed ATPS responds to a wide range of input forces from 0.098 to 724 N in self-powered mode, verifying its feasibility as a tactile sensor for human motion detection and recognition (throat swallowing, wrist bending, elbow bending, knee bending, walking slowly, running fast) and as a pressure sensor (Morse code, digit recognition) and demonstrating its potential for motion tracking, medical rehabilitation, and human-computer interaction.

The Making of Self-Disposing Contactless Motion-Activated Trash Bin Using Ultrasonic Sensors

The spread of viruses continues with the presence of surfaces containing harmful pathogens, posing a prevalent risk of indirect contact transmission. This study aimed to address transmission concerns through the creation of a Self-Disposing Contactless Motion-Activated Trash Bin with the integration of ultrasonic sensors for definite motion detection. A quantitative experimental research design was used to systematically gather data on the parameters of distance, detection time, and weight capacity of the device. The results of the study proved the feasibility of utilizing ultrasonic sensors as a main component in creating a self-disposing contactless trash bin. The device possessed the capability of detecting motion up to 60 centimeters, and as early as 0.47 seconds. Its self-disposing feature has also been deemed functional, with a weight of 1 to 3 kilograms. This study strived to contribute to the burgeoning field of smart waste management by offering a tangible solution that addresses the escalating demand for efficient and contactless waste disposal methods. By bridging technological innovation with pressing societal needs, this study emphasized the potential of sensor- driven solutions in shaping a more sustainable and hygienic future. Based on the findings,the device can detect motion within a fair range, function in less than a second, and self-dispose effectively. It is recommended to use materials of higher quality to enhance and refine the operating process of the self-disposing contactless motion-activated trash bin.

Home Automation System

The world is rapidly moving towards automation as people have less time to handle all the work that needs to be done. Automation is an easy solution to control any product or machine to suit our needs. This article presents the development and implementation of a new home automation system unit using Arduino Nano as the main processing unit. The system integrates multiple sensors such as passive infrared (PIR) sensors for motion detection, gas sensors for monitoring gas issues, temperature sensors for detecting temperature changes, and light sensors for monitoring ambient light, as well as Bluetooth modules for seamless wireless communication and monitoring capabilities. The primary objective of this research is to create a smart and flexible home automation solution that enhances comfort, security, and energy efficiency.

Xanthan gum‐toughened hydrogel for durable strain and pressure sensors

AbstractIonic conductive hydrogels have caught much attention for serving as wearable sensors, however, most hydrogel sensors are difficult to be used for repeated sensing due to low toughness and poor self‐recovery. Here, tough and self‐recovery hydrogels are constructed by introducing xanthan gum into poly(acrylamide‐co‐trimethyl ammonium chloride) (P(Am‐DMC)) hydrogel network. Xanthan gum can bind with P(Am‐DMC) chains via hydrogen bonds and the carboxyl group from xanthan gum generates electrostatic interaction with DMC, thus improving the mechanical toughness and fatigue resistance. Furthermore, the hydrogel is highly sensitive to mechanical deformation and presents durability for repeated stretching or compression, which can be designed as a wearable sensor for human motion detection. It is anticipated that the successful design of xanthan gum‐toughened hydrogel can broaden the application range of hydrogels.

Comprehensive beam delivery latency evaluation for gated proton therapy system using customized multi-channel signal acquisition platform.

Beam delivery latency in respiratory-gated particle therapy systems is a crucial issue to dose delivery accuracy. The aim of this study is to develop a multi-channel signal acquisition platform for investigating gating latencies occurring within RPM respiratory gating system (Varian, USA) and ProBeam proton treatment system (Varian, USA) individually. The multi-channel signal acquisition platform consisted of several electronic components, including a string position sensor for target motion detection, a photodiode for proton beam sensing, an interfacing board for accessing the trigger signal between the respiratory gating system and the proton treatment system, a signal acquisition device for sampling and synchronizing signals from the aforementioned components, and a laptop for controlling the signal acquisition device and data storage. RPM system latencies were determined by comparing the expected gating phases extracted from the motion signal with the trigger signal's state turning points. ProBeam system latencies were assessed by comparing the state turning points of the trigger signal with the beam signal. The total beam delivery latencies were calculated as the sum of delays in the respiratory gating system and the cyclotron proton treatment system. During latency measurements, simulated sinusoidal motion were applied at different amplitudes and periods for complete beam delivery latency evaluation under different breathing patterns. Each breathing pattern was repeated 30 times for statistical analysis. The measured gating ON/OFF latencies in the RPM system were found to be 104.20±13.64ms and 113.60±14.98ms, respectively. The measured gating ON/OFF delays in the ProBeam system were 108.29±0.85ms and 1.20±0.04ms, respectively. The total beam ON/OFF latencies were determined to be 212.50±13.64ms and 114.80±14.98ms. With the developed multi-channel signal acquisition platform, it was able to investigate the gating lags happened in both the respiratory gating system and the proton treatment system. The resolution of the platform is enough to distinguish the delays at the millisecond time level. Both the respiratory gating system and the proton treatment system made contributions to gating latency. Both systems contributed nearly equally to the total beam ON latency, with approximately 100ms. In contrast, the respiratory gating system was the dominant contributor to the total beam OFF latency.

Mussel-inspired resilient hydrogels with strong skin adhesion and high-sensitivity for wearable device

Stretchable and self-adhesive conductive hydrogels hold significant importance across a wide spectrum of applications, including human–machine interfaces, wearable devices, and soft robotics. However, integrating multiple properties, such as high stretchability, strong interfacial adhesion, self-healing capability, and sensitivity, into a single material poses significant technical challenges. Herein, we present a multifunctional conductive hydrogel based on poly(acrylic acid) (PAA), dopamine-functionalized pectin (PT-DA), polydopamine-coated reduction graphene oxide (rGO-PDA), and Fe3+ as an ionic cross-linker. This hydrogel exhibits a combination of high stretchability (2000%), rapid self-healing (~ 94% recovery in 5 s), and robust self-adhesion to various substrates. Notably, the hydrogel demonstrates a remarkable skin adhesion strength of 85 kPa, surpassing previous skin adhesive hydrogels. Furthermore, incorporating rGO within the hydrogel network creates electric pathways, ensuring excellent conductivity (0.56 S m–1). Consequently, these conductive hydrogels exhibit strain-sensing properties with a significant increase in gauge factor (GF) of 14.6, covering an extensive detection range of ~ 1000%, fast response (198 ms) and exceptional cycle stability. These multifunctional hydrogels can be seamlessly integrated into motion detection sensors capable of distinguishing between various strong or subtle movements of the human body.

Biodegradable and flame-retardant cellulose-based wearable triboelectric nanogenerator for mechanical energy harvesting in firefighting clothing

Integrating flexible triboelectric nanogenerators (TENGs) into firefighting clothing offers exciting opportunities for wearable portable electronics in personal protective technology. However, it is still a grand challenge to produce eco-friendly TENGs from biodegradable and low-cost natural polymers for mechanical-energy harvesting and self-powered sensing. Herein, conductive polypyrrole (PPy) and natural chitosan (CS)/phytic acid (PA) tribonegative materials were employed onto the Lycra fabric (LC) in turn to assemble the biodegradable and flame-retardant single-electrode mode LC/PPy/CS/PA TENG (abbreviated as LPCP-TENG). The resultant LPCP-TENG exhibits truly wearable breathability (1378.6 mm/s), elasticity (breaking elongation 291 %), and shape adaptivity performance that can produce an open circuit voltage of 0.3 V with 2 N contact pressure at a working frequency of 5 Hz with a limiting oxygen index of 35.2 %. Furthermore, facile monitoring for human motion of firefighters on fireground is verified by LPCP-TENG when used as self-powered flexible tactile sensor. In addition, degradation experiments have shown that waste LPCP-TENG can be fully degraded in soil within 120 days. This work broadens the applicational range of wearable TENG to reduce the environmental effects of abandoned TENG, exhibiting prosperous applications prospects in the field of wearable power source and self-powered motion detection sensor for personal protection application on fireground.

Smart Printed Triboelectric Wearable Sensor with High Performance for Glove-Based Motion Detection.

In a world increasingly driven by data, wearable triboelectric nanogenerators (TENGs) offer a convenient way to monitor and collect information about human body motions. To meet the demands of the large-scale production of wearable TENGs, material selection to realize a high conversion efficiency and simplify the fabrication process remains a challenge. To address these issues, we present a simple-structured wearable printed arc-shaped triboelectric sensor (PATS) for finger motion detection by leveraging inkjet printing technology. In this regard, pressure sensors composed of diverse materials based on dielectric-dielectric and metal-dielectric structures in contact-separation mode were fabricated and compared. Thanks to the unique characteristics of the silver nanoparticle (Ag-NP)-printed layer and silicon rubber (SR), the SR-Ag PATS shows a high peak-to-peak voltage of 14.15 V and a short-circuit current of 0.78 μA. The proposed sensor with the capability of accurately identifying finger motions at various bending angles suggests promising application potential in glove-based human-machine interface (HMI) systems.