Flexible sensors are used widely in wearable devices, specifically flexible piezoresistive sensors, which are common and easy to manipulate. However, fabricating such sensors is expensive and complex, so proposed here is a simple fabrication approach involving a sensor containing microstructures replicated from a sandpaper template onto which polydimethylsiloxane containing a mixture of graphene and carbon nanotubes is spin coated. The surface morphologies of three versions of the sensor made using different grades of sandpaper are observed, and the corresponding pressure sensitivities and linearity and hysteresis characteristics are assessed and analyzed. The results show that the sensor made using 80-mesh sandpaper has the best sensing performance. Its sensitivity is 0.341 kPa−1 in the loading range of 0–1.6 kPa, it responds to small external loading of 100 Pa with a resistance change of 10%, its loading and unloading response times are 0.126 and 0.2 s, respectively, and its hysteresis characteristic is ∼7%, indicating that the sensor has high sensitivity, fast response, and good stability. Thus, the presented piezoresistive sensor is promising for practical applications in flexible wearable electronics.

  • A piezoresistive flexible sensor is fabricated by replicating microstructures from sandpaper onto a PDMS-RGO-CNT composite.

  • •The sensor exhibits sensing performance with high sensitivity, rapid response, and low hysteresis.

  • •Larger microstructures replicated from sandpaper show better performance compared to smaller ones.

Flexible electronics, wearable electronics, and electronic skin are becoming increasingly prevalent,1–3 and in these applications of electronics, pressure sensors are essential.4–6 However, because traditional semiconductor and metal electrodes are brittle, rigid, and have extremely low tensile capacity, pressure sensors that use such electrodes are unsuitable for applications that require flexible contact, particularly wearable electronics and electronic skin. Instead, flexible pressure sensors have witnessed great progress for the above applications.7 Currently, there are many different types of flexible pressure sensor, such as capacitive,8 piezoelectric,9,10 triboelectric,11 and piezoresistive.12 In particular, the piezoresistive type has attracted widespread attention because of its simple manufacturing processes, strong anti-interference ability, small size, and large deformation range, but problems remain, such as high cost, no mass fabrication, and poor stability.

Many functional nanomaterials are candidates for flexible pressure sensors, and novel strain sensors have been realized recently using such materials. For instance, silver and gold nanowires have been investigated for their near-perfect conductive properties and have been embedded in soft substrates to make flexible or stretchable electronic devices.13–15 However, these metal-based flexible sensors are vulnerable because repeated bending or stretching can easily reduce their performance. Rogers et al. reported various materials and mechanics for stretchable devices, indicating the practical applications for wearable and flexible electronics.16 Amjadi et al. reported sandwich-like polydimethylsiloxane (PDMS) embedded with silver nanowires to achieve highly stretchable properties and repeatable sensing,14 and Gong et al. presented a low-cost fabrication strategy for a wearable and highly sensitive pressure sensor by sandwiching ultrathin gold-nanowire-impregnated tissue paper between two PDMS sheets.15 However, although origami structures such as wavy metal nanosheets on polymeric substrates have great potential for improving the lifetime of flexible sensors, they are quite complicated to fabricate.

Sensors based on carbon nanomaterials exhibit excellent performance because of their superior mechanical and electrical properties.17–22 In many cases, polymeric composites with carbon nanomaterials such as graphene17–19 and carbon nanotubes (CNTs)20–22 are more robust to repeated bending or stretching and thus have practical application potential. Carbon nanomaterials have been reported for applications such as reduced graphene oxide (RGO) for lightweight high-efficiency electromagnetic interference shielding,23 CNT–silica nanocomposites for temperature-dependent microwave attenuation,24 and an acoustic sensor based on MXene/PEDOT:PSS composite for speech recognition and skin-vibration detection.25,26 Lyu et al. proposed a novel bone-inspired fatigue-resistant hydrogel with high-level mechanical and piezoresistive properties based on graphene nanosheet-embedded carbon for use in daily human monitoring.27 Zhang et al. reported the direct fabrication of flexible tensile sensors for an intelligent robotic hand by polariton energy transfer based on graphene nanosheet films.28 Li et al. proposed a type of grid-shape structures embedded with CNTs that exhibits highly sensitive piezoresistivity for high-precision industrial applications.22 Unlike metal nanoparticles or nanowires combined with silicone rubber, their carbon counterparts have significant piezoresistive properties because of their excellent electrical conductivity, flexibility, and stability,29,30 and the aforementioned studies provide much inspiration for designing and applying piezoresistive pressure sensors based on carbon nanomaterials.

In previous work, we presented blade-coating-created silver–graphene nanosheet structures that have piezoresistive properties and are applicable to wearable electronics.31 However, despite performing well at resistive sensing, our previous approach required expensive photolithography to prepare the microstructures. Instead, what is desired is cost-effective and easy fabrication of stable high-performance piezoresistive sensors for use in wearable flexible devices, and a good approach for this is replication from an original template such as readily available sandpaper. Herein, we propose a simple way to create a flexible piezoresistive sensor from PDMS containing CNTs and graphene and given a surface texture from a sandpaper template; then, by simply changing the mesh number of the sandpaper, different microstructures can be prepared for the conductive functional layer of the flexible pressure sensor. By this means, flexible sensors can be prepared without having to use complex processes and expensive equipment, thus greatly reducing the production costs. The as-prepared flexible sensors are tested on a testing platform, and the data are collected and analyzed. As a result, the proposed piezoresistive flexible pressure sensor demonstrates good performance with high sensitivity, fast response, high repeatability, and low hysteresis, as well as wearability for finger motion monitoring.

Monolayer RGO with a purity of 99% was used as purchased from Suiheng Scientific Ltd., China. Multi-walled CNTs with a purity of 95 wt. % were purchased from Hengqiu Scientific Ltd., China. PDMS (Sylgard 184, Dow Corning) was used as the polymer matrix of the composite for the sensor. Anhydrous ethanol (EtOH) was purchased from Zhiyuan Chemicals Ltd., China. Sandpaper with mesh numbers of 80, 400, and 800 was used as the templates of the microstructures. An ultrasonic cleaner, a spin coater (Spin-50; Kaimei Ceramics, China), and a hotplate were used for drying the samples and curing the CNT-RGO-PDMS composites.

The sandpaper with different mesh numbers was cut into rectangular sheets to match the dimensions of the glass slides used in the study, after which the sheets were cleaned in deionized water using the ultrasonic cleaner to remove any contaminant adhering to the surface and then dried on the hotplate. Double-sided adhesive tape was then used to bond the dried sandpaper sheets to the glass slides.

The RGO and multi-walled CNTs were weighed out with a mass ratio of 2:1 using an electronic balance, then this simple combination of carbon nanomaterials was poured into a glass beaker containing a certain amount of EtOH. The glass beaker was then placed in the ultrasonic cleaner, and after 20 min of ultrasonic treatment, the contents of the beaker were mixed well. The uniformly dispersed carbon solution was then poured onto the sandpaper on the glass slides, which were then placed on the hotplate to evaporate the solvent; this procedure was repeated three times to allow the carbon material to adhere to the surface of the sandpaper as evenly as possible, thus making the conductive layer more uniform.

PDMS and curing agent were mixed with a mass ratio of 10:1 and stirred thoroughly, followed by degassing in a vacuum chamber. The PDMS mixture was then poured onto the sandpaper with carbon nanomaterial mixture, and a thin film of PDMS was obtained by spin coating, followed by further degassing in the vacuum chamber. By this means, the PDMS filled the cavities on the sandpaper under vacuum, thus taking on the surface morphology of the sandpaper as well as covering the carbon nanomaterials. After curing in an oven at 60 °C, each sample was peeled off from its sandpaper template to obtain a thin film of PDMS-RGO-CNT composite. Because of the manner of processing, only the side that had been in contact with the sandpaper was electrically conductive, not the smooth and flat side. The PDMS-RGO-CNT composite sample with replica sandpaper structure was then cut into small 1 × 1 cm2 pieces, each of which was then glued onto a piece of copper foil using a conductive silver paste. Finally, a Kapton membrane was used to package the sample into a resistive flexible pressure sensor.

The morphology of the microstructures replicated from the sandpaper was characterized using a confocal microscope (LEXT OLS5000; Olympus, Japan), with a vacuum chamber used to degas the PDMS mixture so that the microstructures could be obtained. A tensile tester was used to apply pressure in the range of 0–20 kPa in order to measure the resistivity response of the flexible pressure sensors under loading, with the characteristics and performance of the as-prepared sensors assessed using a source measure unit (model 2450; Keithley) in conjunction with the digital-display tensile tester (HP-200; Edberg, China).

Herein, we propose a simple piezoresistive flexible pressure sensor that comprises an active layer of elastic PDMS-RGO-CNT conductive composite and two electrodes. When loading pressure is applied to the sensor, its output resistance changes accordingly. The total resistance of the flexible sensor comprises those of the active layer and the electrodes, but the electrode resistance is generally fixed, so the response of the resistance signal of the flexible sensor is determined mainly by the active layer. The resistance is expressed as
R=ρls,
(1)
where ρ is the intrinsic resistivity the composite material, l is the length of the conductive material, and s is the cross-sectional area. As can be seen, the change in resistance depends on the material itself, so the choice of flexible materials is very important, along with the geometric parameters of length and cross-sectional area. The resistive flexible pressure sensor presented herein comprises a flexible substrate and a conductive polymer composite, and its resistance response to external force is due to the piezoresistive effect, which is the combined effect of the surface contact resistance and bulk resistance.
When subjected to an external load, the active layer of the flexible pressure sensor undergoes deformation of its surface microstructure, resulting in a change in the contact area of the conductive surface and thus leading to greater number of conductive paths (Fig. 1). This phenomenon is known as the surface contact resistance effect, and the surface contact resistance RS is given by
RSKρP,
(2)
where ρ is the electrical resistivity of the contact surface, P is the applied load, and K is a constant related to the contact surface.
FIG. 1.

Schematics of mechanism of piezoresistive pressure sensor during (a) unloading and (b) loading.

FIG. 1.

Schematics of mechanism of piezoresistive pressure sensor during (a) unloading and (b) loading.

Close modal
Furthermore, when a flexible pressure sensor is subjected to an external force, the overall thickness of the polymer composite film decreases as the distance between the internal conductive materials decreases, and when that distance reaches the tunneling gap, current is generated by field-emission electrons or tunneling electrons.32 By this means, more conductive paths are generated and thus the resistance decreases. This phenomenon is known as the bulk piezoresistive effect, which is described as
R=lPkwt2Rmm,
(3)
where P is the external load, k is the number of conductive paths per unit area, t is the number of conductive particles in each conductive path, m is the total number of conductive particles, Rm is the resistance of the conductive particles, and l and w are the length and width of the sensor, respectively.

By replication from the sandpaper to the PDMS composite, a conductive functional microstructure layer is formed with the RGO-CNTs embedded uniformly in the PDMS matrix. Compared to the CNTs structures produced by sputtering or coating methods, the presented CNTs composite matrix can be more robust in conductivity and repeatability. In this study, sandpaper with different grid numbers was used as a microstructure template to prepare the piezoresistive flexible pressure sensors, and the surface morphology of the obtained microstructures was observed and analyzed using a laser confocal microscope, as shown in Fig. 2. As can be seen, using the 80-mesh sandpaper as a template results in the fewest microstructures per unit area, and these are the largest ones, with heights of 20–150 µm. By contrast, using the 800-mesh sandpaper results in the most microstructures per unit area, and these are the smallest ones, with heights of only 7–15 µm; these microstructures would enable resistive sensors with large sensitivity.

FIG. 2.

Morphological characterization of surface morphology of conductive layer of flexible resistive sensor: (a) photograph of as-prepared sensor; (b) microscopy images of surface morphologies of replicas from sandpaper with different microstructures; (c) profiles indicating roughness of surface morphology from 80-, 400-, and 800-mesh sandpaper.

FIG. 2.

Morphological characterization of surface morphology of conductive layer of flexible resistive sensor: (a) photograph of as-prepared sensor; (b) microscopy images of surface morphologies of replicas from sandpaper with different microstructures; (c) profiles indicating roughness of surface morphology from 80-, 400-, and 800-mesh sandpaper.

Close modal
The sensitivity S of the resistive flexible pressure sensor is characterized by the variation of the resistance per unit load change, given by
S=(RR0)/R0ΔP=ΔR/R0ΔP,
(4)
where R is the output resistance of the flexible sensor subjected to external load P, and R0 is its initial resistance.

We applied loading of 0–20 kPa to the flexible sensor and obtained its output by using a source meter (Keithley 2450). The tested sensor samples were square in shape and had dimensions of 10 × 10 mm2. Figure 3 shows the resistance response curves of resistive flexible pressure sensors made with 80-, 400-, and 800-mesh sandpaper under external loading of 0–20 kPa. As can be seen, the resistance decreases with increasing applied load, and there are two main stages in this loading range. During the first stage corresponding to 0–5 kPa, the resistance decreases steeply, whereas in the second stage corresponding to 5–20 kPa, it decreases very slowly. Figure 3 shows that the resistance of the flexible resistive pressure sensor prepared from the 80-, 400-, and 800-mesh sandpaper as the template is initially 40.45, 15.87, and 428.09 kΩ, respectively, under zero load, decreasing to 12.37, 6.71, and 206.5 kΩ, respectively, when the external load is increased to 20 kPa.

FIG. 3.

Resistive response and sensitivity of flexible sensors made with (a) 80-mesh, (b) 400-mesh, and (c) 800-mesh sandpaper, and (d) comparison of the resistance sensitivities of the three microstructure replicas.

FIG. 3.

Resistive response and sensitivity of flexible sensors made with (a) 80-mesh, (b) 400-mesh, and (c) 800-mesh sandpaper, and (d) comparison of the resistance sensitivities of the three microstructure replicas.

Close modal

In the loading range of 0–1.6 kPa, the sensitivity of the flexible resistive pressure sensor resulting from the 80-, 400-, and 800-mesh sandpaper template is 0.341, 0.251, and 10.226 kPa−1, respectively; this range corresponds to large deformation of the surface microstructures of the resistive flexible sensor subjected to external loading, leading to a dramatic change in resistance. In the loading range of 1.5–4.2 kPa, the respective sensitivity is 0.044, 0.041, and 0.040 kPa−1, and the curve is much less steep; this range corresponds to compressive deformation of most the underlying microstructures. In the loading range of 4.3–20 kPa, the respective sensitivity is 0.0046, 0.0041, and 0.0032 kPa−1; in this range, the loading has saturated and the microstructure deformation becomes rather small, thus leading to decreased sensitivity. Comparison shows that the flexible pressure sensor fabricated using the 80-mesh sandpaper has the highest sensitivity of the three sensors in the loading range of 0–1.6 kPa, and the reason for this is likely to be that the 80-mesh sandpaper results in the largest microstructures and hence the best deformation and highest toughness.

Compared to the maximum pressure detection limit, the minimum one is far more important in the practical application of pressure sensors. For instance, detecting the human pulse with very weak pressure demands a flexible pressure sensor with high sensitivity at a lower pressure detection limit. Figure 4(a) shows the different output resistances of the flexible pressure sensor made using the 80-mesh replica as the functional microstructure under small external loads. As can be seen, the resistance change of the flexible pressure sensor reaches ∼10% under a small external load of 100 Pa, and the change is consistent. The flexible PDMS substrate has excellent mechanical properties, and the surface microstructure is prone to large deformation under external load. The flexible pressure sensor shows a large response signal, which meets the requirements of applications in flexible wearable electronic devices. Furthermore, Fig. 4(b) shows the fast repeatability of the resistance change upon applying varying loading and unloading at a pressure of 1 kPa.

FIG. 4.

(a) Resistance response of flexible sensor for different load pressures, and (b) repeatability of resistance response under varying loading and unloading at a pressure of 1 kPa.

FIG. 4.

(a) Resistance response of flexible sensor for different load pressures, and (b) repeatability of resistance response under varying loading and unloading at a pressure of 1 kPa.

Close modal

The response time is the time interval between the input pressure load and the output resistance, and it reflects the response speed of the flexible sensor under external load. The shorter the response time, the lower the signal delay of the flexible pressure sensor, thereby ensuring the timeliness of signal detection and better meeting the needs of actual measurement. In particular, when using a flexible pressure sensor as a control element in the form of a switch or button for a flexible electronic device, it is necessary to use one with a fast response and no jamming delay. Here, we use a load of 20 kPa and a loading rate of 10 mm s−1 to load and unload the flexible sensor with the 80-mesh replica, and its output response curve is recorded at a sampling frequency of 25 Hz. As can be seen from Fig. 5, when an external load is applied, the resistance of the flexible pressure sensor changes rapidly, with a response time of 126 ms. After holding the external load for a period of time, the loading is then released, whereupon the resistance recovers to its initial value, and the observed recovery time is ∼200 ms. As can be seen, the flexible sensor has a short response time, which is due to the better deformability of the 80-mesh replica. A small applied load leads to deformation and results in a large resistance change. Although the response and recovery times are not perfectly small, they nevertheless meet most common requirements for human motion, robotic sensation, stretching, and other aspects.

FIG. 5.

Response characteristics of flexible sensor prepared by using 80-mesh sandpaper as template: (a) one period of test for response and recovery upon loading and then unloading; (b) response time; (c) recovery time.

FIG. 5.

Response characteristics of flexible sensor prepared by using 80-mesh sandpaper as template: (a) one period of test for response and recovery upon loading and then unloading; (b) response time; (c) recovery time.

Close modal

Testing the repeatability of the flexible pressure sensor involves assessing its output upon being subjected to continuous cyclic loading and unloading, reflecting its durability. The purpose of doing so is to expand the range of use of sensors in some complex environments. In addition, certain requirements need to be put forward for prolonging the service life of the sensor to maintain high output performance after many times of loading and unloading. Figure 6(a) shows that the sensor can still recover to its initial resistance upon repeated loading and unloading under a load of 20 kPa. Meanwhile, after 100 cycles of loading and unloading, the output curve of the tested flexible pressure sensor does not exhibit significant variation in output performance. As can be seen from Fig. 6(b), the sensor can still recover to its initial state after many cycles of the same loading and unloading under a certain pressure of finger pressing, indicating that the sensor has good stability and meets the requirement in practical applications. The output characteristic curves corresponding to the first and 100th times were obtained through 100 times of loading and unloading (with a loading range of 0–20 kPa) in repeated tests of the flexible resistive pressure sensor prepared from the 80-mesh replica. Figure 6(b) shows the repeatability output performance curve of the flexible sensor under a pressure load of 20 kPa.

FIG. 6.

Repeatability test of flexible resistive pressure sensor prepared with 80-mesh replica from sandpaper: (a) resistive response of sensor during repeated loading and unloading under a pressure of 20 kPa; (b) comparison of responses in first and 100th tests.

FIG. 6.

Repeatability test of flexible resistive pressure sensor prepared with 80-mesh replica from sandpaper: (a) resistive response of sensor during repeated loading and unloading under a pressure of 20 kPa; (b) comparison of responses in first and 100th tests.

Close modal
An ideal sensor has a linear relationship between input and output, but most sensors used in practical applications have a nonlinear input–output relationship. Therefore, to facilitate calibration in practical applications, it is common to approximate the performance curve of a flexible sensor. For example, to linearize the input–output relationship, tangent or secant lines can be used to approximate the actual input–output curve within a certain range, or circuit compensation can be used to linearize the curve. Figure 7(a) shows the actual output characteristic curve obtained by experimental testing, which is nonlinear. There are errors between the fitting curve and the actual output curve, and the maximum error is referred to as the nonlinear error, commonly expressed as the relative error (i.e., linearity), representing the degree of inconsistency between the fitted straight line and the output curve. This is given by
δl=ΔymaxRmax,
(5)
where ∆ymax is the maximum difference between the actual characteristic curve and the fitting line, and Rmax is the full-scale output value.
FIG. 7.

Linear fit and hysteresis test: (a) actual output curve and line fitted using least-square method; (b) hysteresis test of flexible sensor.

FIG. 7.

Linear fit and hysteresis test: (a) actual output curve and line fitted using least-square method; (b) hysteresis test of flexible sensor.

Close modal

We used the least-square method to calculate the fitting line shown in Fig. 7(a), whose slope is −9.87 ± 1.36 and whose intercept is 32.15 ± 1.25. As can be seen, the R2 value (coefficient of determination) is ∼0.9636, which suggests an acceptable linear fit in the range of 0.2–1.6 kPa.

Figure 7(b) shows the resistance output response curves of the flexible pressure sensor made with the 80-mesh replica during loading and unloading in the range of 0–20 kPa. As can be seen, there is a gap between the two curves, and this is because the measured sensor comprises mainly PDMS, which is incompressible and requires a relatively long recovery time upon unloading, resulting in resistance hysteresis. The hysteresis of the flexible sensor is described as
E=RloadRunloadRmax×100%,
(6)
where Rload and Runload are the resistance outputs under the same load during loading and unloading, respectively, and Rmax is the maximum output response of the resistance. From Eq. (6), the hysteresis characteristic of the measured resistive flexible pressure sensor is 7%, indicating that it has small hysteresis, good sensing performance, and high accuracy and reliability.

To demonstrate the performance of the as-prepared resistive flexible pressure sensor, we mounted it on the outermost joint of an index finger. During the test, the output resistance of the sensor changed with bending of the finger, thereby allowing the extent of bending motion of the finger to be monitored. The test results are shown in Fig. 8, where stage 1 shows the initial resistance of the flexible pressure sensor corresponding to the unbent state of the finger. As the finger was bent during stage 2, the output resistance of the sensor decreased, then it recovered to the same resistance as in stage 1 when the finger bending angle returned to that in stage 1. Furthermore, after bending the sensor to larger angles in stages 3 and 4, the output resistance of the sensor still returned to the initial resistance. This was due to the robust and stable performance of resistive flexible sensor, which will surely enable potential applications for flexible manipulators and wearable electronic devices. The above results reveal the potential of the sensor’s fast response, good repeatability, satisfactory linearity, long-term durability, and low hysteresis, thus showing its robustness and applicability in practical applications.

FIG. 8.

Demonstration of as-prepared pressure sensor: (a) flexible sensor mounted on index finger to monitor bending motion with stages 1–4; (b) resistance measured during stages 1–4.

FIG. 8.

Demonstration of as-prepared pressure sensor: (a) flexible sensor mounted on index finger to monitor bending motion with stages 1–4; (b) resistance measured during stages 1–4.

Close modal

In summary, herein we demonstrated a simple flexible resistive sensor made using readily available sandpaper as a microstructure template. We compared three versions of the flexible sensor with microstructures formed from 80-, 400-, and 800-mesh sandpaper by spin coating and replicating onto a PDMS composite of RGO and CNTs. The results revealed the good performance of the resistive flexible pressure sensor, including its relatively high sensitivity, fast response, high repeatability, good linearity, and low hysteresis. In the loading range of 0–1.6 kPa, the sensitivity of the flexible resistive pressure sensor made with the 80-, 400-, and 800-mesh replica was 0.341, 0.251, and 0.226 kPa−1, respectively, showing that the 80-mesh resistive flexible sensor had the highest sensitivity. In addition, a high sensitivity was obtained under a pressure as low as 100 Pa, with a resistance change of 10%, a response time of 126 ms, a recovery time of 200 ms, and a hysteresis characteristic of ∼7%. A demonstration of the resistive flexible pressure sensor mounted on a finger joint revealed good repetitive performance during the bending process, indicating potential applications in flexible electronic devices.

This work was supported financially by the Science and Technology Cooperation and Exchange Special Project of Shanxi Province (Grant No. 202204041101006), the Fundamental Research Program of Shanxi Province (Grant Nos. 20210302123013, 202203021222077, and 202203021222069), and the Shanxi Scholarship Council of China (Grant No. 2023-130).

The authors have no conflicts to disclose.

The data that support the findings of this study are available within the article.

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Huifen Wei received a Ph.D. degree from the School of Instruments and Electronics at the North University of China in 2022 and is currently a lecturer in its School of Mechanical Engineering. Her current research interests are mainly in the micro/nanofabrication of wearable flexible sensors.

Xiangmeng Li received a Ph.D. degree from the State Key Laboratory for Manufacturing System Engineering at Xi’an Jiaotong University in 2016 and is currently an associate professor in the School of Mechanical Engineering at the North University of China. He was a CSC visiting scholar in KU Leuven, Belgium during 2022 to 2023. His current research interests are mainly in ultraprecision manufacturing technology and micro/nanofabrication for soft robotic actuation and sensing.

Fangping Yao received a Master’s degree from the School of Mechanical Engineering at the North University of China in 2022. Her current research interests are mainly in the fabrication of wearable flexible sensors.

Xinyu Feng received a Ph.D. degree from Jilin University in 2017 and is currently a lecturer in the School of Mechanical Engineering at the North University of China. Her current research interests are mainly in intelligent manufacturing technology.

Xijing Zhu is currently a professor and the dean of the School of Mechanical Engineering at the North University of China. He is vice-chairman of the Shanxi Mechanical Engineering Association and the dean of the Shanxi Key Laboratory of Advanced Manufacturing Technology. He earned his Ph.D. from Nanjing University of Aeronautics and Astronautics and currently leads a research group on ultraprecise nontraditional machining and intelligent manufacturing technologies. He has received many prizes and honors, including the Second Prize of the Shanxi Natural Science Award in 2021.