Electromechanical Performance Research Articles

Next-gen strain sensors: Self-healing, ultra-sensitive, lightweight, and durable MWCNT-silicone rubber for advanced human motion tracking

Strain sensors that have flexible wearable forms can be applied in different aspects, such as in soft robotics, human-computer interaction, motion monitoring, and medical treatment process. The main challenge is creating lightweight, flexible sensors with high sensitivity. In this study, we developed flexible strain sensors using a simple sandwich manufacturing method. To achieve this, multi-walled carbon nanotubes (MWCNTs) were chosen for their excellent conductivity, while silicone rubber (SR) provided a flexible and durable substrate. Advanced SEM-EDX and FTIR analyses were conducted to assess the material structure. Furthermore, the electromechanical performance of the sensors was thoroughly evaluated, highlighting their potential in real-world applications. Electromechanical performance evaluation showed that the SR/0.7-MWCNT/SR sensor in the 0–90 % strain range had a sensitivity of 34.47, an increase of 53.35 %, and a linearity of 0.978, an increase of 10 % compared to the SR/0.5-MWCNT/SR sensor. In addition, the sensor has extremely fast response and recovery times of 65 ms and 60 ms, respectively. The sensor is also able to withstand up to 1.200 cycles of stretching, twisting, and bending. The sensor also exhibited good autonomous electromechanical self-healing properties against physical damage. The sensor developed in the present study are proven to be used to detect human movements such as finger bending, wrist, elbow, and knee movements.

Dynamic electromechanical characterizations of poly(vinylidene fluoride) based nanocomposite films on ultra‐low modulus polymer substrate

AbstractThis article explores the electromechanical performance of poly(vinylidene fluoride) (PVDF) films with silver nanoplatelets on smooth polydimethylsiloxane (PDMS) substrates. PVDF, a semi‐crystalline polymer, shows piezoelectric properties when processed at low temperatures, making it ideal for energy harvesting and sensors. This research addresses a gap by examining high strain rate and complex electromechanical characteristions of PVDF composites, which are underexplored. Films, fabricated using a non‐vacuum rod coating method, underwent dynamic electromechanical tests (strain rate ~ 2 s−1), including stretching, twisting, combined stretching and twisting, and forced vibrations. Results show the films function up to 17% applied strain with a gage factor of 10.57. In twisting tests, the laminates perform up to 387° in slow twisting (gage factor = 28.34) and 341° in fast twisting (gage factor = 7.65). Combined stretching and twisting tests show performance decreases, with functionality up to 6.24% strain at a twist angle of 330.1°. Vibration tests reveal that increased amplitude reduces performance, with the laminates enduring frequencies between 4.35 and 12.14 Hz. The films also exhibit a linear piezoelectric response, with a maximum open circuit voltage of 37.2 V under an impact load of 1112 N, underscoring the potential of PVDF/Ag nanocomposites for advanced MEMS applications.

Natural fibers for performance boosting of BaTiO3-PDMS flexible piezoelectric composite generators

Among biobased materials, date palm leaf fiber (DPLF) is a cellulose-rich fiber with considerable potential for use in sustainable composites, where it can improve mechanical properties and reduce weight. In this study, a flexible piezoelectric generator (PEG) composed of a polydimethylsiloxane (PDMS) polymer, lead-free barium titanate (BaTiO3), and DPLF are presented. A comparative analysis assessed the impact of incorporating DPLF through morphological, mechanical, and electrical evaluations. The results indicate that DPLF improves the performance of the PEG while maintaining desirable mechanical properties, such as flexibility and durability. The improved performance can be attributed to the enhanced dielectric properties, robustness, and distribution of the piezoceramic particles. PEG (5 wt% DPLF + 15 wt% BaTiO3) exhibits a maximum open-circuit voltage twice that of 15 wt% BaTiO3 PEG (6 V) and an eightfold higher power density (8 μW/cm2). These findings result from an increased dielectric constant of 6.8 and a favorable capacitance of 30 pF. Incorporating cellulose-rich DPLF significantly impacts the electromechanical performance of the PDMS/BaTiO3-DPLF composite due to several beneficial effects, including good particle dispersion, sustainability, improved homogeneity, and improved dielectric properties.

Dual design strategy for carboxymethyl cellulose-polyaniline composite hydrogels as super-sensitive amphibious sensors

Conductive hydrogels as ideal candidate materials for flexible sensors have exhibited many promising applications. However, complex application environments, such as low temperatures or underwater conditions, have introduced new requirements for hydrogel sensors. Herein, a high-performance conductive hydrogel based on carboxymethyl cellulose-polyaniline (CMC-PANI) submicron spheres, poly (vinyl alcohol) (PVA) and phytic acid (PA) was designed and fabricated via a dual design strategy. CMC-PANI particles were introduced to not only empower the good electromechanical performance to the hydrogels, but also enhance the mechanical properties. The obtained hydrogel exhibited good mechanical property, anti-freezing, anti-swellable behavior and recyclable performance. Resistive-type strain sensors assembled by the prepared hydrogels exhibited high pressure sensitivity (34.17×10−2 kPa−1) and fast response time (100 ms), which can clearly detect the pulse beats. Moreover, the hydrogel sensors can achieve long-term stability, high sensitivity and fatigue resistance as an underwater sensor. Based on these favorable performances, the conductive polymer hydrogels may open up an enticing avenue for functional soft materials in health diagnostic and electronic components.

Wire-to-two-drop plasma thruster: Experimental and numerical investigation of electroaerodynamic jet flow for micro aerial vehicle propulsion

Conventional micro aerial vehicles (MAVs) have primarily relied on complex, flapping-wing mechanisms for propulsion, often exhibiting limitations in terms of reliability and efficiency. To overcome these challenges, this study explores the potential of electroaerodynamic (EAD) thrusters as a novel propulsion system. By accelerating air molecules through ion collisions, EAD jet flow generates thrust, offering advantages such as noiseless operation and zero emissions due to its moving-part-free design. This research presents a comprehensive experimental and numerical investigation of a wire-to-two-drop thruster configuration to elucidate its electromechanical performance, plasma flow dynamics, and EAD jet characteristics. Experimental measurements of key parameters, including current, thrust, power, and effectiveness, were correlated with numerical simulations, demonstrating excellent agreement with a maximum error below 5%. These findings align strongly with established theoretical frameworks, revealing an inverse square root relationship between effectiveness and thrust. To optimize thruster performance, optimal operating voltages were identified at approximately 8.2, 9.4, and 11.6 kV for inter-electrode gap distances of 10, 15, and 20 mm, respectively, achieving a balanced trade-off between thrust and effectiveness. Detailed numerical visualizations of the plasma flow field, including velocity distribution, jet morphology, potential distribution, and electric field lines, provided valuable insights into the thruster's operation. Building upon these insights, a proof-of-concept EAD flier was constructed and tested, incorporating a serrated emitter electrode and lightweight materials. This flier achieved a mass of 0.5 g and generated a thrust of 0.77 g at 15 kV, resulting in a thrust-to-weight ratio of 1.54 and successful liftoff. This demonstration highlights the potential of EAD propulsion for practical MAV applications.

Ultrahigh Electrostrictive Effect in Lead-Free Sodium Bismuth Titanate-Based Relaxor Ferroelectric Thick Film.

In recent years, the development of environmentally friendly, lead-free ferroelectric films with prominent electrostrictive effects have been a key area of focus due to their potential applications in micro-actuators, sensors, and transducers for advanced microelectromechanical systems (MEMS). This work investigated the enhanced electrostrictive effect in lead-free sodium bismuth titanate-based relaxor ferroelectric films. The films, composed of (Bi0.5Na0.5)0.8-xBaxSr0.2TiO3 (BNBST, x = 0.02, 0.06, and 0.11), with thickness around 1 μm, were prepared using a sol-gel method on Pt/TiO2/SiO2/Si substrates. By varying the Ba2+ content, the crystal structure, morphology, and electrical properties, including dielectric, ferroelectric, strain, and electromechanical performance, were investigated. The films exhibited a single pseudocubic structure without preferred orientation. A remarkable strain response (S > 0.24%) was obtained in the films (x = 0.02, 0.06) with the coexistence of nonergodic and ergodic relaxor phases. Further, in the x = 0.11 thick films with an ergodic relaxor state, an ultrahigh electrostrictive coefficient Q of 0.32 m4/C2 was achieved. These findings highlight the potential of BNBST films as high-performance, environmentally friendly electrostrictive films for advanced microelectromechanical systems (MEMS) and electronic devices.

Strong pinning effect on domains in piezoelectrics

In high-power applications, since mechanical losses in piezoelectric devices always result in considerable heat generation, the temperature stability of the mechanical quality factor (Qm) is particularly crucial and should be considered in real piezoelectric applications. Here, we propose a poling-aging-repoling strategy to make the defect dipoles aligned with the poling direction as much as possible, thereby resulting in the strong pinning of ferroelectric domains. A giant internal bias field Ei (11.6 kV cm−1 @ 1 Hz) and a high Qm (2074), accompanied by almost unchanged d33, are obtained in the composition of CuO-doped (K0.48Na0.52)0.94Li0.06Nb0.94Ta0.06O3 (KNNLT-Cu) ceramics with a diffused polymorphic phase transition. Furthermore, and this is more encouraging, the high electromechanical performance exhibits good temperature stability in the range from room temperature to 100 °C, suggesting that the thermal stability of Qm can be effectively improved by combining the strong pinning of defect dipoles with composition design and providing a way for the development and design of future high-power piezoelectric devices.

The structural evolution and electric field-induced strain performance of Bi0.5(Na0.41K0.09)TiO3–Ba(Fe0.5Sb0.5)O3 lead-free piezoelectric ceramics

In recent years, lead-free Bi0.5Na0.5TiO3 (BNT) based piezoelectric ceramics with excellent strain properties have gained widespread recognition for their application in high-precision displacement actuators. The (1-x)(0.82Bi0.5Na0.5TiO3-0.18K0.5Bi0.5TiO3)-xBa(Fe0.5Sb0.5)O3 ceramics were fabricated through the die-pressing method in this work. The effect of BFS introduction on the dielectric, ferroelectric and microstructure characteristics of BNKT ceramics was systematically investigated. Among these compositions, the BNKT-0.015BFS ceramics exhibited a piezoelectric strain coefficient (d33*) of 658 pm/V at an electric field of 55 kV/cm, while achieving a strain response of 0.51 % at 85 kV/cm. The observed improvement in strain performance can be attributed to the evolution from non-ergodic relaxor state to ergodic relaxor state caused by BFS substitution. Furthermore, transmission electron microscopy (TEM) explicitly confirmed coexistence of rhombohedral and tetragonal phase and revealed the morphology of nanosized domains. This study adds to a deeper comprehension of the characteristics of strain response enhancement in BNT-based ceramics, opening up avenues for designing novel lead-free piezoelectric ceramics with outstanding electromechanical performance.

Research progress in the study of textured piezoelectric ceramics

Piezoelectric ceramics have the advantages of uniform composition, excellent performance, good electromechanical coupling performance, and high cost performance. They are currently one of the important materials for manufacturing sensors and semiconductor components on the market. Although piezoelectric ceramic materials are widely used because of their many advantages, how to improve their piezoelectric properties is still a hot and difficult research spot. Previously, the piezoelectric properties of piezoelectric ceramics were affected by adjusting the grain size, but due to its limited enhancement effect, researchers hope to find other ways to improve the piezoelectric properties of ceramics more efficiently. Research has found that texture process can enable isotropic ceramics to obtain similar characteristics to single crystals that exhibit anisotropy. This greatly improves the piezoelectric properties of ceramics. During the texture process, the type and content of the template, texture degree and texture orientation, and other factors will significantly affect the piezoelectric properties of textured ceramics. With the continuous development of texture technology and process, the piezoelectric properties of textured ceramics have been significantly improved, but the practical application is less. Based on this, this article expounds the design principles of textured ceramics, summarizes the progress in the preparation of textured piezoelectric ceramics, and systematically explains the importance of template and texture orientation selection in texture processing. Finally, this paper also analyses the application of textured ceramics, and looks forward to the optimization methods and development prospects of piezoelectric ceramics. It is hoped to help the application and development of piezoelectric ceramics.

Investigating the effect of rolling deformation on the electro-mechanical limits of Nb3Sn wires produced by RRP® and PIT technologies

Future high-field magnets for particle accelerators hinge on the crucial development of advanced Nb3Sn wires engineered to withstand the large stresses generated during magnet assembly and operation. The superconducting properties of Nb3Sn enable the design of compact accelerator-quality magnets above 10 T, but at the same time the brittleness and strain sensitivity of the material impose careful consideration of the mechanical limits. In addition, accelerator magnets are wound using Rutherford cables and the cabling process generates deformations in the wire that can affect its electro-mechanical performance. This paper reports on the impact of the rolling deformation on the transverse stress tolerance of high-performance restacked-rod-process (RRP®) and powder-in-tube (PIT) Nb3Sn wires. Rolling deformation was used to mimic the effect of cabling on the wire shape. Deformed samples were compared to reference round wires in term of stress dependence and irreversible limit (σ irr) of the critical current (I c) under transverse compressive loads up to 240 MPa. Experiments were performed at 4.2 K, 19 T, on resin-impregnated single wires that imitate the operating conditions in a Rutherford cable of an accelerator magnet. The results show that rolling deformation has a detrimental effect on the initial I c of PIT wires, but it does not influence the behavior of the wire under stresses above 70 MPa. On the other hand, the deformation of RRP® wires leads to an improved σ irr without affecting the initial I c. Additionally, a 2D-mechanical finite element method model of the RRP® wire was developed to investigate the impact of the wire geometry on the plastic deformation of the copper matrix, which induces residual stresses on Nb3Sn and is the main cause for the permanent reduction of I c. Based on the model results, an alternative layout of the wire was proposed that improves its stress tolerance without affecting its electrical transport properties.

Electromechanical coupling in polyetheretherketone through flexoelectricity

The electrical signals generated by an electromechanical coupling mechanism in biomaterials have significant potential applications in the field of biomedical engineering. For example, the piezoelectric- or flexoelectric-induced electrical signals in bone biomaterials play an important role in facilitating self-repair, remodeling, and reshaping processes. Polyetheretherketone (PEEK) has been found to possess excellent mechanical properties and biocompatibility with bone, making it an outstanding choice as an implantable polymer material. It is particularly important to investigate the electromechanical response performance of PEEK materials. In this study, we experimentally examine the flexoelectricity of PEEK and evaluate its effective out-of-plane direct and converse flexoelectric coefficients. Using the piezoresponse force microscopy module of atomic force microscopy, we observe a clear converse flexoelectric effect in a PEEK disk-shaped sample. The effective out-of-plane converse flexoelectric coefficient of the PEEK disk-shaped sample is about μ3333eff=0.21 ± 0.02 nN/V. The effective out-of-plane direct flexoelectric coefficient, determined through the bending experiment of a PEEK cantilever, is f3113eff = 17.61 nC/m, which is larger than that of polyvinylidene fluoride and is nearly two orders of magnitude superior over other biomaterials such as bone and hydroxyapatite. This indicates that PEEK materials have even greater potential for development and research in biomedical engineering applications such as intervertebral fusion, bone joint replacement, bone rehabilitation and regeneration, etc.

PNN-PST-PT ferroelectric ceramics with ultrahigh piezoelectricity and superior electromechanical performance for high quality piezo-sensors

A novel ferroelectric ceramic system, Pb(Ni1/3Nb2/3)O3–Pb(Sc1/2Ta1/2)O3–PbTiO3 (PNN-PST-PT), with ultrahigh piezoelectricity and super electromechanical performance is developed. The microstructure and crystal structure of PNN-PST-PT ceramics, along with their electrical properties, were examined regarding PNN content. The results indicated that the room-temperature dielectric constant was considerably enhanced with PNN content increasing and the values of Pr, Pmax, and Ec steadily declining. The optimal performance was achieved in the 0.4PNN-0.235PST-0.365 PT composition with a high piezoelectric coefficient (d33) of 1028 pC/N and an electromechanical coupling factor (kp) of 0.69. Strong piezoelectric response is attributed to the coexistence of R and T phases as well as the enhanced relaxation characteristics, which manifest as a specific polarization configuration resulting from the local structural distortion caused by the co-occupation of ions with different radii at the B-site. These suggest that PNN-PST-PT ceramics can be a desirable material for applications in high-quality piezosensors, actuators, etc.

Thermal and electromechanical performance in BaSnO3-modified potassium sodium niobate piezoceramics via two-step sintering

In view of industrial applications requiring high piezoelectric activity, KNN-based ceramics face two key constraints: insufficient density and temperature sensitivity. To address these challenges, this study first introduces BaSnO3 and employs two-step sintering method (TSS) for fabrication, thereby synthesizing ternary 0.975K0.5Na0.5NbO3-0.025Bi0.5K0.5TiO3-xBaSnO3 (KNN-1000xBaSn; x = 0, 0.3 %, 0.6 % and 0.9 %) with superior piezoelectricity (d33 = 217–257 pC/N; d33* = 265–330 pm/V; S = 0.16–0.21 %), high Curie temperature (TC = 325–349 °C) and densification (4.3–4.5 g/cm3; relatively density ∼96 %). In one respect, the TSS allows minimal volatilization of alkali metals while promoting grain homogenization. In another respect, the introduction of BaSnO3 enhances the mobility of domain walls, meanwhile fosters diffuse phase transitions (DPT) and widens dielectric peaks without significantly impairing TC. Moreover, the KNN–6BaSn obtain not only reinforced d33 (256 pC/N) with high TC (325 °C) and ε′ (1016), but also fatigue resistance and extreme-temperature endurance with excellent d33* (445 pm/V at 90 °C; 300 pm/V at 180 °C). This work provides a resultful dual-strategy for the emergence of lead-free piezoelectric products.

A stretchable and self-powered strain sensor with elastomeric electret

Stretchable deformation sensors play an important role in the perception and autonomy of soft robots. While various sensors have been reported, the mechanical sensor with self-powered capability and stretchability to suit extreme environment is urgently required. In this study, a stretchable, self-powered, sensitivity adjustable, and long-term stability strain sensor based on the stretchable electret is researched for deformation monitoring. This stretchable and self-powered sensor is composed of the dielectric elastomer with designed elastic modulus gradient and the stretchable electret with elastomeric and Nano-particles. The electro-mechanical capability of this designed sensor is researched and optimized by multi-objective optimization approach. The sensor exhibits self-powered capability, stretchability (tensile strain from 0% to 20%), tunable sensitivity (optimized from 5.7 to 5.9 pC mm−1), and stability, where electromechanical performance remains stable after 8000 stretching cycles. The feasibility of its autonomous sensing which promotes a wide range of potential application in soft robotics is demonstrated. This elastic modulus gradient-induced and net charge design significantly broadened the potential applications with large deformation and low-attached stiffness.

Facile printing of liquid–metal-based stretchable conductor using EGaIn/Ga2O3 composite

Printing gallium-based liquid metals (LMs) poses a significant challenge due to their high surface tension. In this work, we introduce a printable LM-based conductor using an EGaIn/Ga2O3 composite. This composite is achieved through a simple mixing process and is suitable for scalable stencil printing. The blend ratio of EGaIn/Ga2O3 is optimized to create LM pastes with an excellent balance of printability and electromechanical performance. Using these developed LM pastes, we successfully demonstrate a stretchable strain sensor with a gauge factor of 2 for monitoring human hand gestures. Additionally, we showcase a stretchable LED array deformable for up to 100% strain.

Monitoring of cementitious materials hydration using 2–2 cement-based piezoelectric transducers based on electromechanical impedance method

Monitoring cementitious materials hydration enhances construction efficiency by providing crucial information regarding the optimal timing for shoring removal and pre-stress transferring. In recent years, many scholars have utilized the lead zirconate titanate (PZT)-based electromechanical impedance method (EMI) to monitor the cementitious materials hydration process. However, conventional piezoelectric transducers are less compatible with cementitious materials. In addition, the currently commonly used statistical-based metrics lack a clear physical meaning. The 2–2 cement-based transducer (2−2), composed of multiple PZT elements, demonstrates excellent electromechanical performance and good compatibility with cementitious materials. In this study, the 2–2 was employed to monitor the cementitious materials hydration, and an electromechanical impedance model for describing the interaction between the 2–2 and the structure was presented. Taking into account both resonance frequency and peak value of the conductance signatures, an objective function was defined. Genetic algorithm (GA) was employed to minimize the disparity between theoretical and experimental results, thus extracting equivalent stiffness and damping. The empirical relationship between equivalent stiffness, damping, and compressive strength was established to predict the compressive strength. The experimental results show that for the same monitoring process, the normalized equivalent stiffness and damping extracted from different 2–2 sensors are in some agreement. It is more sensitive to hydration processes than statistical indicators. More importantly, the equivalent parameters have a clear physical meaning and can better portray the hydration process of the cementitious materials.

Bone Fracture Healing under the Intervention of a Stretchable Ultrasound Array.

Ultrasound treatment has been recognized as an effective and noninvasive approach to promote fracture healing. However, traditional rigid ultrasound probe is bulky, requiring cumbersome manual operations and inducing unfavorable side effects when functioning, which precludes the wide application of ultrasound in bone fracture healing. Here, we report a stretchable ultrasound array for bone fracture healing, which features high-performance 1-3 piezoelectric composites as transducers, stretchable multilayered serpentine metal films in a bridge-island pattern as electrical interconnects, soft elastomeric membranes as encapsulations, and polydimethylsiloxane (PDMS) with low curing agent ratio as adhesive layers. The resulting ultrasound array offers the benefits of large stretchability for easy skin integration and effective affecting region for simple skin alignment with good electromechanical performance. Experimental investigations of the stretchable ultrasound array on the delayed union model in femoral shafts of rats show that the callus growth is more active in the second week of treatment and the fracture site is completely osseous healed in the sixth week of treatment. Various bone quality indicators (e.g., bone modulus, bone mineral density, bone tissue/total tissue volume, and trabecular bone thickness) could be enhanced with the intervention of a stretchable ultrasound array. Histological and immunohistochemical examinations indicate that ultrasound promotes osteoblast differentiation, bone formation, and remodeling by promoting the expression of osteopontin (OPN) and runt-related transcription factor 2 (RUNX2). This work provides an effective tool for bone fracture healing in a simple and convenient manner and creates engineering opportunities for applying ultrasound in medical applications.

Enhanced electromechanical performance of Nafion actuator doped by poly(ethylene glycol)‐grafted graphene oxide

AbstractCurrent ionic polymer–metal composite (IPMC) actuators have severe actuation drawbacks (i.e. low force output and poor stability), hampering their applications. To address these issues, poly(ethylene glycol)‐grafted graphene oxide (PEG‐GO) is synthesized and incorporated into a Nafion matrix, thus producing a PEG‐GO hybrid Nafion film with better physiochemical properties for fabricating a high‐performance, low‐cost IPMC actuator. The modification of PEG to GO not only prevents GO agglomeration and sedimentation, but also avoids loss of PEG in water. Driven by a 0.2 Hz, 2.5 V electric field, the hybrid IPMC actuator exhibits superior electromechanical behaviors, i.e. a swing angle of 110.3°, a blocking force of 6.89 mN and a stable working time of 485 s, respectively increasing by 92%, 209% and 294% when compared to a pure Nafion actuator. © 2024 Society of Chemical Industry.

Exploring the Elastomer Influence on the Electromechanical Performance of Stretchable Conductors.

Stretchable electronics has received major attention in recent years due to the prospects of integrating electronics onto and into the human body. While many studies investigate how different conductive fillers perform in stretchable composites, the effect of different elastomers on composite performance, and the related fundamental understanding of what is causing the performance differences, is poorly understood. Here, we perform a systematic investigation of the elastomer influence on the electromechanical performance of gold nanowire-based stretchable conductors based on five chemically different elastomers of similar Young's modulus. The choice of elastomer has a huge impact on the electromechanical performance of the conductors under cyclic strain, as some composites perform well, while others fail rapidly at 100% strain cycling. The lack of macroscopic crack formation in the failing composites indicates that the key aspect for good electromechanical performance is not homogeneous films on the macroscale but rather beneficial interactions on the nanoscale. Based on the comprehensive characterization, we propose a failure mechanism related to the mechanical properties of the elastomers. By improving our understanding of elastomer influence on the mechanisms of electrical failure, we can move toward rational material design, which could greatly benefit the field of stretchable electronics.

Compressive stress reduction in sputter-deposited yttrium aluminum nitride (Y0.2Al0.8N) thin films for BAW resonators with high electromechanical coupling

In the past decade, rare earth elements have found increasing interest in enhancing the piezoelectric coefficient of aluminum nitride (AlN) thin films. Until now, scandium has been the most successful rare earth element to enhance the piezoelectric coefficient (d33) up to 600 %. In this research paper, we present a 250 % increase in d33 to 12.5 pC/N for sputter-deposited yttrium alloyed aluminum nitride (Y0.2Al0.8N) thin films compared to pure AlN. However, this increase in d33 comes with a substantial increase in compressive layer stress well above 1 GPa. Therefore, a chamber pressure sweep technique is introduced, resulting in a 40 % reduction in the stress level without significantly affecting the crystallographic film parameters to facilitate device integration. Even more, high compressive stress in thin films is a critical concern in piezoelectric MEMS devices such as bulk acoustic wave (BAW) resonators, as it can adversely affect the piezoelectric material properties and hence, the electromechanical performance. For this purpose, we demonstrate that the pressure sweep technique improves the electromechanical coupling factor of Y0.2Al0.8N to 7.02 %, being substantially above the reference value of 6.02 % set by pure AlN. In summary, the findings from this study may stimulate further effort to integrate YxAl1-xN thin films in BAW filter devices for future telecommunication applications.