A High-performance Bending Strain Sensor Based on Piezoelectric Stack

Antonis Lamia^*
*Correspondence: Antonis Lamia, Department of Metallurgical Engineering and Materials, Federal University of Ouro Preto, Ouro Preto, Brazil, Email:

Introduction

The development of high-performance bending strain sensors is crucial in various applications, including structural health monitoring, wearable electronics, robotics, and biomedical devices. A promising approach to achieving high sensitivity, durability, and efficiency is through the utilization of piezoelectric stacks. Piezoelectric materials exhibit the ability to generate an electric charge in response to mechanical deformation, making them ideal candidates for strain sensing applications. By employing a stacked configuration, these sensors can enhance their signal output, improve mechanical robustness, and achieve superior performance compared to traditional single-layer piezoelectric sensors. Piezoelectric stacks consist of multiple layers of piezoelectric material, typically arranged in a series or parallel configuration to optimize electrical and mechanical properties. The stacking method enhances the strain sensitivity and overall mechanical strength, making them highly suitable for detecting bending strains in dynamic and harsh environments. When subjected to bending forces, the layers experience deformation, leading to charge generation that can be accurately measured. The response of the sensor is directly related to the piezoelectric coefficient of the material, the number of layers in the stack, and the mechanical properties of the substrate and encapsulating materials.

Description

One of the significant advantages of using a piezoelectric stack-based bending strain sensor is its ability to maintain high efficiency even under repeated mechanical loading. Traditional strain sensors often suffer from material fatigue, signal degradation, and limited durability over time. In contrast, piezoelectric stacks distribute the mechanical stress across multiple layers, reducing localized stress concentrations and enhancing longevity. This characteristic is particularly important in applications where continuous monitoring is required, such as in aerospace structures, bridges, and advanced robotics. The efficiency of a piezoelectric strain sensor is largely influenced by the choice of piezoelectric material. Commonly used materials include Lead Zirconate Titanate (PZT), barium titanate, and Polyvinylidene Fluoride (PVDF). PZT is one of the most widely utilized materials due to its high piezoelectric coefficient and excellent electromechanical coupling properties. However, concerns regarding lead content in PZT have led to research into alternative lead-free piezoelectric materials such as Potassium Sodium Niobate (KNN) and Bismuth Ferrite Oxide (BFO). These materials offer promising piezoelectric properties while addressing environmental and health concerns associated with lead-based compounds. Another critical factor in the performance of bending strain sensors is the design and integration of electrodes. The electrode configuration significantly affects the sensorâ??s ability to capture and transmit signals efficiently. Interdigitated Electrodes (IDEs) and parallel plate electrodes are commonly used configurations in piezoelectric sensors. IDEs are particularly advantageous for enhancing charge collection efficiency and improving signal-to-noise ratio [1].

Additionally, advancements in nanomaterial-based electrodes, such as graphene and silver nanowires, have further enhanced the sensitivity and flexibility of piezoelectric sensors. To optimize the performance of piezoelectric stack-based bending strain sensors, researchers have explored various fabrication techniques. Additive manufacturing, sol-gel processing, and sputtering deposition are among the most commonly employed techniques to achieve precise material properties and structural integrity. The integration of Microelectromechanical Systems (MEMS) technology has also facilitated the development of miniaturized and highly efficient sensors with improved spatial resolution. Furthermore, flexible and stretchable substrates have enabled the creation of wearable strain sensors for real-time health monitoring applications. The real-world applications of high-performance piezoelectric stack-based strain sensors are vast and diverse. In the field of structural health monitoring, these sensors are deployed in critical infrastructures such as bridges, pipelines, and buildings to detect early signs of mechanical failure. Continuous monitoring using these sensors enables timely maintenance, reducing the risk of catastrophic failures and extending the lifespan of structures. The aerospace industry also benefits from piezoelectric strain sensors by incorporating them into aircraft wings and fuselage components to monitor structural integrity and prevent fatigue-related failures [2,3].

In the biomedical sector, piezoelectric stack-based bending strain sensors have found applications in prosthetics, rehabilitation devices, and wearable health monitors. These sensors can accurately track limb movement, muscle activity, and joint strain, providing valuable data for medical professionals to assess patient recovery and optimize treatment plans. Additionally, their integration into smart textiles has paved the way for advanced wearable technology capable of monitoring vital signs and detecting abnormal physiological conditions in real time. The field of robotics has also leveraged piezoelectric bending strain sensors to enhance tactile sensing and proprioception in robotic limbs and exoskeletons. These sensors provide precise feedback on force and movement, allowing robots to perform delicate tasks with improved dexterity and responsiveness. The incorporation of machine learning algorithms further enhances the interpretability of sensor data, enabling more intelligent and adaptive robotic systems. Despite the numerous advantages of piezoelectric stack-based bending strain sensors, challenges remain in their widespread adoption. One of the primary limitations is the brittleness of certain piezoelectric materials, which can lead to fractures under excessive mechanical stress. To address this issue, researchers have been exploring the development of composite materials that combine the high piezoelectric response of ceramics with the flexibility of polymers. These hybrid materials offer improved mechanical resilience while maintaining high sensitivity. Another challenge is the influence of environmental factors such as temperature fluctuations, humidity, and electromagnetic interference on sensor performance [4,5].

Conclusion

Advanced packaging techniques and the incorporation of protective coatings have been investigated to mitigate these effects and enhance the reliability of sensors in harsh environments. Additionally, the development of self-powered piezoelectric sensors, which harvest ambient energy for operation, has gained significant interest as it eliminates the need for external power sources and enhances deployment versatility. Future advancements in piezoelectric stack-based bending strain sensors are expected to focus on improving material properties, miniaturization, and integration with wireless communication systems. The advent of the Internet of Things (IoT) has opened new possibilities for remote sensing applications, where real-time data transmission and cloud-based analysis can provide valuable insights for predictive maintenance and health monitoring. Furthermore, the exploration of bio-inspired designs and novel nanostructured materials holds great potential for enhancing the sensitivity and functionality of next-generation strain sensors. In conclusion, the development of a high-performance bending strain sensor based on piezoelectric stacks represents a significant advancement in the field of sensor technology. The combination of high efficiency, mechanical strength, and enhanced sensitivity makes these sensors ideal for a wide range of applications, from structural health monitoring to biomedical devices and robotics. Ongoing research and technological innovations continue to address existing challenges, paving the way for more reliable, durable, and intelligent sensing solutions in the future.

Acknowledgement

None.

Conflict of Interest

None.

References

1. Toron, BartÅ?omiej, Piotr Szperlich, Marian Nowak and Alicja Starczewska. "A novel method for measuring piezoelectric coefficients." Measure 206 (2023): 112274.

Google Scholar Cross Ref Indexed at

2. Kim, Kyungrim, Jinwook Kim, Xiaoning Jiang and Taeyang Kim. "Static force measurement using piezoelectric sensors." J Sens 2021 (2021): 6664200.

Google Scholar Cross Ref Indexed at

3. Seethaler, Rudolf, Sepehr Zarif Mansour, Michael G. Ruppert and Andrew J. Fleming. "Position and force sensing using strain gauges integrated into piezoelectric bender electrodes." Sens Actuators A Phys 321 (2021): 112416.

Google Scholar Cross Ref Indexed at

4. Seethaler, Rudolf, Sepehr Zarif Mansour, Michael G. Ruppert and Andrew J. Fleming. "Piezoelectric benders with strain sensing electrodes: Sensor design for position control and force estimation." Sens Actuators A Phys 335 (2022): 113384.

Google Scholar Cross Ref Indexed at

5. Suzuki, Atsushi, Wang Liao, Daiki Shibata and Yuki Yoshino, et al. "Structural damage detection technique of secondary building components using piezoelectric sensors." Bldg 13 (2023): 2368

Google Scholar Cross Ref Indexed at