Dynamic Force Sensor Research Articles

Abraded optical fibre-based dynamic range force sensor for tissue palpation

Tactile information acquired through palpation plays a crucial role in relation to surface characterisation and tissue differentiation - an essential clinical requirement during surgery. In the case of Minimally Invasive Surgery, access is restricted, and tactile feedback available to surgeons is therefore reduced. This paper presents a novel stiffness controllable, dynamic force range sensor that can provide remote haptic feedback. The sensor has an abraded optical fibre integrated into a silicone dome. Forces applied to the dome change the curvature of the optical fibres, resulting in light attenuation. By changing the pressure within the dome and thereby adjusting the sensor’s stiffness, we are able to modify the force measurement range. Results from our experimental study demonstrate that increasing the pressure inside the dome increases the force range whilst decreasing force sensitivity. We show that the maximum force measured by our sensor prototype at 20 mm/min was 5.02 N, 6.70 N and 8.83 N for the applied pressures of 0 psi (0 kPa), 0.5 psi (3.45 kPa) and 1 psi (6.9 kPa), respectively. The sensor has also been tested to estimate the stiffness of 13 phantoms of different elastic moduli. Results show the elastic modulus sensing range of the proposed sensor to be from 8.58 to 165.32 kPa.

Experimental study on the mechanical characteristics of a novel high-strength-and-high-toughness steel

To effectively control large deformation disasters, our team has developed a novel high-strength and high-toughness (HSHT) steel. This study aims to conduct a comparative analysis of the mechanical properties of HSHT steel and typical commercial steel under tension and impact. Testing was carried out using a universal testing machine and a self-developed drop-hammer-type longitudinal impact dynamic mechanical tester, with dynamic axial force sensors and infrared equipment utilized for monitoring. The results of the experiments are as follows: In the tensile test, HSHT steel exhibited superior performance in terms of tensile strength, elongation, and uniform deformation, particularly in radial deformation. The strength-ductility product of HSHT steel was more than two times that of typical commercial steel, indicating better energy-absorbing properties. Infrared data analysis showed that HSHT steel bars displayed uniform warming throughout their entire length. In the impact test, HSHT steel reinforcement demonstrated higher mechanical properties compared to commercial steel. Following failure, HSHT steel bars did not exhibit significant necking at the fracture site and showed a larger area of impact deformation. The axial forces experienced by the different steel bars were similar under various conditions. Data fitting analysis revealed an exponential relationship between the static tensile maximum strains of all bar types and the number of cyclic impacts. For HSHT steel bars, the number of impacts was also exponentially related to displacement, cyclic height, and energy absorbed prior to failure. Additionally, HSHT bars exhibited better uniform heating characteristics during cyclic impacts, with higher heating temperatures compared to typical commercial steels.

Advancing Dynamic Polymer Mechanochemistry through Synergetic Conformational Gearing.

Harnessing mechanical force to modulate material properties and enhance biomechanical functions is essential for advancing smart materials and bioengineering. Polymer mechanochemistry provides an emerging toolkit for exploring unconventional chemical transformations and modulating molecular structures through mechanical force. One of the key challenges is developing innovative force-sensing mechanisms for precise and in situ force detection. This study introduces mDPAC, a dynamic and sensitive mechanophore, demonstrating its mechanochromic properties through synergetic conformational gearing. Its unique mechanoresponsive mechanism is based on the simultaneous conformational synergy between its phenazine and phenyl moieties, facilitated by a worm-gear-like structure. We confirm mDPAC's complex mechanochemical response and elucidate its mechanotransduction mechanism through our experimental data and comprehensive simulations. The compatibility of mDPAC with hydrogels is particularly notable, highlighting its potential for applications in aqueous biological environments as a dynamic force sensor. Moreover, mDPAC's multicolored mechanochromic responses facilitate direct force sensing and visual detection, paving the way for precise and real-time mechanical force sensing in bulk materials.

On-demand fabrication of piezoelectric sensors for in-space structural health monitoring

Inflatable structures, promising for future deep space exploration missions, are vulnerable to damage from micrometeoroid and orbital debris impacts. Polyvinylidene fluoride-trifluoroethylene (PVDF-trFE) is a flexible, biocompatible, and chemical-resistant material capable of detecting impact forces due to its piezoelectric properties. This study used a state-of-the-art material extrusion system that has been validated for in-space manufacturing, to facilitate fast-prototyping of consistent and uniform PVDF-trFE films. By systematically investigating ink synthesis, printer settings, and post-processing conditions, this research established a comprehensive understanding of the process-structure-property relationship of printed PVDF-trFE. Consequently, this study consistently achieved the printing of PVDF-trFE films with a thickness of around 40 µm, accompanied by an impressive piezoelectric coefficient of up to 25 pC N−1. Additionally, an all-printed dynamic force sensor, featuring a sensitivity of 1.18 V N−1, was produced by mix printing commercial electrically-conductive silver inks with the customized PVDF-trFE inks. This pioneering on-demand fabrication technique for PVDF-trFE films empowers future astronauts to design and manufacture piezoelectric sensors while in space, thereby significantly enhancing the affordability and sustainability of deep space exploration missions.

The influence of surgical technique guidance and surgeon's experience on the femoral head assembly in total hip arthroplasty.

The importance of the assembly procedure on the taper connection strength is evident. However, existent surgical technique guides frequently lack comprehensive and precise instructions in this regard. The aim of our experimental study was to evaluate the influence of the surgical technique guide on the femoral head assembly procedure in surgeons with differing levels of experience in total hip arthroplasty. Twenty-eight participants, divided into four groups based on their lifetime experience in total hip arthroplasty, conducted a femoral head assembly procedure in a simulated intraoperative environment before and after reviewing the surgical technique guide. Demographic information and the number of hammer blows were documented. Hammer velocity and impaction angle were recorded using an optical motion capturing system, while the impaction force was measured using a dynamic force sensor within the impactor. We observed a high variation in the number of hammer blows, maximum force, and impaction angle. Overall, the number of hammer blows decreased significantly from 3 to 2.2 after reviewing the surgical technique guide. The only significant intragroup difference in the number of hammer blows was observed in the group with no prior experience in total hip arthroplasty. No correlation was found between individual factors (age, weight, height) or experience and the measured parameters (velocity, maximum force and angle). The present study demonstrated a high variation in the parameters of the femoral head assembly procedure. Consideration of the surgical technique guide was found to be a limited factor among participants with varying levels of experience in total hip arthroplasty. These findings underline the importance of sufficient preoperative training, to standardize the assembly procedure, including impaction force, angle, and use of instruments.

Transparent Piezoelectric Nanogenerator for Self-Powered Force Sensing Applications

Piezoelectric materials have been widely used as dynamic force sensors, accelerometers, and energy harvesters. Herein, we report the poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TrFE)) based transparent piezoelectric nanogenerator (PENG) as a self-powered force sensor. The 2 × 2 array of PENGs was fabricated by sandwiching the P(VDF-TrFE) film between two indium tin oxide-based electrodes. The device demonstrated good stable and repeatable piezoelectric response (sensitivity of 0.3 V N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ), which increased linearly with externally applied compressive force. The output voltage of the devices varied with the frequency of the external force application, and they showed a sensitivity of 0.25 V Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> between 2 and 10 Hz frequency. The excellent dynamic force sensing response, transparency, and self-power feature make presented devices ideally suited for applications such as see-through smart plaster that allow wound healing monitoring without removing the plaster.

Flexible Dynamic Pressure Sensor for Insole Based on Inverse Viscoelastic Model

The quantification of the plantar arch load and its surface distribution is essential to improve locomotion in many sports as well as rehabilitation protocols for patients. This article has a threefold objective. First, it focuses on the design, fabrication, and characterization of dynamic force sensors, based on both a single and multilayer of Velostat piezoresistive polymer. A matrix of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9\times $ </tex-math></inline-formula> 3 flexible pressure sensors has been developed to analyze and recognize plantar movements. Second, two models linking the plantar pressure to the resistance of the piezoresistive material, with and without taking into account the viscoelastic nature of the piezoresistive material, are proposed. Finally, an inversion of the models is employed in order to estimate plantar pressure as a function of the variation in material resistance. An evaluation of the plantar pressure for various movements is also proposed.

Recyclable cardanol-based benzoxazines with multi-stimulus-responsive shape-memory and their carbon nanotubes composites for dynamic force sensor

The development of reprocessable and multi-stimulus-responsive shape memory benzoxazines and their carbon nanotubes composites on intelligence sensor still presents significant challenges. Herein, complete leveraging of the long alkyl chain of cardanol containing dioxaborolanes resulted in the multi-stimulus-responsive shape memory cardanol-based benzoxazines, showing multiple responses such as heat, microwave, light, and even water. The cardanol-based benzoxazines could recover to their permanent shape within 15 s at 80 °C, while 700 s was needed when exposed to IR light at 1.8 W/cm2. Microwaves with an output of 800 W can trigger the restoration of permanent shape in 57 s. Water can be used to improve the plasticity of cardanol-based benzoxazines, allowing them to be processed into a variety of geometries. Cardanol-based benzoxazines with dioxaborolanes exhibited a tensile strength of up to 25.82 MPa, representing a 9-fold increase from a control sample without dioxaborolanes. Shape memory cardanol-based benzoxazine/carbon nanotubes composite also possesses great sensitivity to varied pressures and bending, as well as high stability and recoverability, owing to the presence of CNTs and dioxaborolanes. The newly fabricated recycled cardanol-based benzoxazine with multi-response shape memory characteristics described here should inspire the design of sustainable electronic materials for multipurpose sensing.

Counting the Cost of Inaccurate Modeling in Vibration Testing

What happens when you conduct a force-limited vibration test on a billion dollar satellite and do not determine stiffness correctly for dynamic force sensors mounted on the shaker?

MXene-enhanced β-phase crystallization in ferroelectric porous composites for highly-sensitive dynamic force sensors

Piezoelectric polyvinylidene fluoride (PVDF) has been widely utilized in flexible and self-powered tactile sensors, which require high ferroelectricity of polar phase PVDF. Herein, we demonstrate self-powered piezoelectric e-skins with high sensitivity and broad sensing range based on 3D porous structures of MXene (Ti 3 C 2 T x )/PVDF. MXene was used as a nucleation agent to increase the ferroelectric properties of PVDF. This was carried out considering its 2D geometry and abundant surface functional groups that facilitate intermolecular hydrogen bonding between the surface functional groups of MXene and the CH 2 group of PVDF. In addition, porous structures can increase the variation in contact area and localized stress concentration in response to applied pressure. This further enhances the piezoelectric sensitivity. Owing to structural deformation and localized stress concentration, the piezoelectric sensitivity of porous MXene/PVDF e-skin is 11.9 and 1.4 nA kPa −1 for low (< 2.5 kPa) and high (2.5–100 kPa) pressure ranges, respectively. These are 31 and 3.7 times higher, respectively, than that of planar MXene/PVDF e-skin (0.4 nA kPa −1 for <100 kPa). In addition, porous MXene/PVDF e-skin exhibits a broad sensing range of up to 100 kPa, and stable sensing performance (5000 repetitions). Our piezoelectric porous MXene/PVDF e-skins enable the monitoring of high-frequency dynamic signals such as acoustic sound waves as well as low-frequency radial artery pulses. In particular, the detection of high-frequency vibrations from sliding friction enables our sensor array to perceive various surface textures with different roughness and moduli, as well as the spatial distribution of words embossed on surfaces. This demonstrates its substantial potential for application in wearable devices, prosthetic limbs, robotics, and healthcare monitoring devices. MXene with a large specific surface area and abundant functional groups can be used as a heterogeneous nucleation agent to induce crystallization of the polar β-phase and enhance the ferroelectric properties of PVDF, which enables the monitoring of high-frequency dynamic signals such as acoustic sound waves as well as low-frequency radial artery pulses. In particular, the detection of high-frequency vibrations from sliding friction enables our sensor array to perceive various surface textures with different roughness and moduli, as well as the spatial distribution of words embossed on surfaces. • High-performance piezoelectric skin sensor is demonstrated using 3D porous structures of MXene (Ti 3 C 2 T x )/PVDF composites. • MXene is used as a nucleation agent to induce polar β-phase and enhance the ferroelectric properties of PVDF. • MXene/PVDF sensor perceives various surface textures as well as the spatial distribution of words embossed on surfaces.

Model-Based Research on Deviation in Dynamic Force Sensor Calibration Process

For dynamic force calibration, it is essential to accurately determine the force applied to a force sensor. The dynamic force calibration device at Changcheng Institute of Metrology and Measurement uses a laser interferometer to measure the impact force of a falling mass. However, due to the base vibration and inertia forces, the force calculated through the hammer acceleration measured by the laser interferometer and the force measured by the sensor are different. This difference can be observed in calibration experiments by comparing the signals obtained by the laser interferometer and the calibrated force sensor. To correct the deviation and explain this difference, three models are proposed and analyzed in this study. The three models were designed using different degrees of freedom according to different dynamical hypotheses. A lnear fitting approach was used to identify the model parameters. To verify the model and parameters, a simulation model was obtained, and it was calculated using SIMULINK. Subsequently, the simulation model was compared to the experimental data. The results in this study show that the three-degree-of-freedom model can accurately reflect the dynamic behavior of the calibration device. Therefore, the measured reference force can be corrected to obtain the force measured using the force sensor through a quantitative model of this kind, and this correction can improve the dynamic force sensor calibration process.

Liquid metal-integrated ultra-elastic conductive microfibers from microfluidics for wearable electronics

Liquid metal (LM) has shown potential values in different areas. Attempts to implement LM are tending to develop new functions and make it versatile to improve its performance for practical applications. Here, we present an unprecedented LM-integrated ultra-elastic microfiber with distinctive features for wearable electronics. The microfiber with a polyurethane shell and an LM core was continuously generated by using a sequenced microfluidic spinning and injection method. Due to the precise fluid manipulation of microfluidics, the resultant microfiber could be tailored with tunable morphologies and responsive conductivities. We have demonstrated that the microfiber could act as dynamic force sensor and motion indicator when it was embedded into elastic films. In addition, the values of the LM-integrated ultra-elastic microfiber on energy conversions such as electro-magnetic or electro-thermal conversions have also been realized. These features indicate that LM-integrated microfiber will open up new frontiers in LM-integrated materials and the wearable electronics field.

A High Dynamic Range Closed-Loop Stiffness-Adjustable MEMS Force Sensor

We present a microelectromechanical system (MEMS)-based closed-loop force sensor, capable of measuring bidirectional forces along one axis of motion. The device comprises an on-chip electrothermal displacement sensor and electrostatic actuators. It features a voltage-controlled stiffness-adjustment mechanism, providing the user with an additional means of tuning the sensor’s characteristics. This silicon-on-insulator device is an improvement on our previous design, offering a better dynamic range and a less complex calibration process. The sensor is fabricated based on a standard SOI MEMS process. It is then fully characterized and instrumented with a feedback controller. The closed-loop characterization reveals a ${1 {\sigma }}$ -resolution of 4.74 nN and a force sensing range of $- {211.7\, {\mu }\text {N}}$ to $\mathrm {211.5\, {\mu }N}$ , leading to a dynamic range of 92.9 dB. [2019-0248]

Dynamic force measurements on swimming Chlamydomonas cells using micropipette force sensors.

Flagella and cilia are cellular appendages that inherit essential functions of microbial life including sensing and navigating the environment. In order to propel a swimming microorganism they displace the surrounding fluid by means of periodic motions, while precisely timed modulations of their beating patterns enable the cell to steer towards or away from specific locations. Characterizing the dynamic forces, however, is challenging and typically relies on indirect experimental approaches. Here, we present direct in vivo measurements of the dynamic forces of motile Chlamydomonas reinhardtii cells in controlled environments. The experiments are based on partially aspirating a living microorganism at the tip of a micropipette force sensor and optically recording the micropipette’s position fluctuations with high temporal and sub-pixel spatial resolution. Spectral signal analysis allows for isolating the cell-generated dynamic forces caused by the periodic motion of the flagella from background noise. We provide an analytic, elasto-hydrodynamic model for the micropipette force sensor and describe how to obtain the micropipette’s full frequency response function from a dynamic force calibration. Using this approach, we measure the amplitude of the oscillatory forces during the swimming activity of individual Chlamydomonas reinhardtii cells of 26 ± 5 pN, resulting from the coordinated flagellar beating with a frequency of 49 ± 5 Hz. This dynamic micropipette force sensor technique generalizes the applicability of micropipettes as force sensors from static to dynamic force measurements, yielding a force sensitivity in the piconewton range. In addition to measurements in bulk liquid environment, we study the dynamic forces of the biflagellated microswimmer in the vicinity of a solid/liquid interface. As we gradually decrease the distance of the swimming microbe to the interface, we measure a significantly enhanced force transduction at distances larger than the maximum extent of the beating flagella, highlighting the importance of hydrodynamic interactions for scenarios in which flagellated microorganisms encounter surfaces.

Development of Large-Range Dynamic Three-Component Sensor

Currently, the vast majority of sensor applied in the field of dynamic testing is piezoelectric sensor, Piezoelectric sensors over 200t are very difficult to produce, However, the traditional strain sensor is not suitable for dynamic testing due to its insufficient frequency response, The large-range strain type dynamic three-component force sensor developed in this paper has been successfully applied in high-speed rail collision test experiment, which breaks the monopoly of piezoelectric sensor in the field of dynamic test and has a broad application prospect.

Online visual monitoring and ultrasonic feedback detection in the ultrasonic precision bonding of polymers

Ultrasonic bonding is a convenient bonding technology, which features sufficient cleanliness, high efficiency, no need for additional bonding aids, and other outstanding advantages. In recent years, it has been introduced into the field of the micro–nano assembly of polymer micro–nano devices, but it is still difficult for current ultrasonic bonding technology to meet the accuracy requirements of the micro–nano assembly. To improve the control accuracy of the hot-melt interface in the process of ultrasonic bonding, an online hot-melt interface monitoring method and an online ultrasonic transmission efficiency detection method are proposed in this article. With these detection methods, the real-time monitoring of the hot-melt interface can be realized on the basis of machine vision, while high-frequency dynamic force sensors can be used to detect the ultrasonic vibration transmitted from the ultrasonic horn to the anvil. Based on these methods, a functional anvil based on visual monitoring and ultrasonic detection is developed, the finite element method has been used to analyze the transmission characteristics of ultrasonic vibration, and experiments are carried out regarding online detection in the process of ultrasonic bonding. The results show that this system can realize the online detection of the hot-melt interface and ultrasonic transmission information, providing a new control method for ultrasonic bonding technology.

Calibration of Dynamic Force Sensors by the Deformation Method

The deformation method of determining the metrological characteristics of variable-force measuring instruments is proposed and examined. The method consists in the excitation of variable forces by a piezoactuator and measurement of the proportional deformation of the elastic calibrated element by a laser interferometer. Unit transfer is shown from the State Primary Standard of units of length, velocity, and acceleration during oscillating motion of a rigid body under GET 58-2018, and the State Primary Standard of force, GET 32-2011. The uncertainty budgets of the determination of metrological characteristics by the known load mass method and the proposed method were compared. A schematic of a measuring installation implementing the proposed method is shown.

Enhanced pseudo-piezoelectric dynamic force sensors based on inkjet-printed electrostrictive terpolymer

Abstract Printed electromechanical devices are an alternative approach for the fabrication of integrated force sensor networks on large-area flexible polymer foils. In the present contribution, we report on a novel parallel-plates capacitive force sensor device based on an electrostrictive poly(vinylidenefluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) terpolymer that exhibited the best electromechanical coupling effect through the drop-on-demand (DoD) inkjet printing technology. Since the ejection of a printable ink droplet is one of the most essential steps for inkjet printing, the adaptable printing parameters depending on the ink delivery system as well as ink formula rheology were first investigated. Successfully printed patterns rely on a controlled drying process of the inks deposited on the flexible polyimide foil, which was also discussed. The substrate temperature was increased for achieving homogeneous polymer patterns. Such a printing technique eventually made it possible to obtain flawless polymer thin layers of several microns, preventing the devices from the risk of electrical failure due to short-circuiting. The capacitive devices were evaluated by proposition of a dynamic force sensor. Sensor devices based on an electrostrictive terpolymer were induced to yield significant polarization thanks to a bias voltage whereas a sensor device of poly(vinylidenefluoride-trifluoroethylene) P(VDF-TrFE) copolymer must be poled under a high electric field with a very high risk of breakdown failure. The pseudo-piezoelectric coefficient d 33 e q was a strict function of the applied electric field and reached as high as 81.6 pC N−1 under 33.33 V/ μ m . The fabrication process in the present study holds high potential in large-area printed terpolymer sensor networks without a poling process as each sensor corresponds to a pixel of the sensing array.

Unmanned Aerial Vehicle Impacts on Heat-Strengthened Glass

Increasing demand for small unmanned aerial vehicles (UAVs) in the logistics and rescue fields, which are closely related to urban environments, has been accompanied by an increase in impact risk to people and property. However, safety regulations for small UAVs in urban areas have not yet been well established, and there are very few studies investigating the collisions between UAVs and building structures that could occur in an urban area. In this study, experimental and numerical investigations are conducted to evaluate the damage resulting from a UAV collision with heat-strengthened glass, a widely used building exterior cladding. Commercially available UAVs were impacted into a series of glass panels at various speeds and angles. The collision processes were recorded with a high-speed camera, and the impact forces of the UAVs were measured using dynamic force sensors. A numerical model of the UAV was then developed to simulate the impacts using the finite element method and verified by comparison with the experimental results. The collision tests performed in this study are expected to provide primary data for establishing UAV safety regulations, and the verified numerical model can be applied to evaluate various collision scenarios for the different UAVs.

Calibration of dynamic force sensors by the deformation method

Calibration of dynamic force sensors by the deformation method