Flexible pressure sensors have been widely used in health detection, robot sensing, and shape recognition. The micro-engineered design of the intermediate dielectric layer (IDL) has proven to be an effective way to optimize the performance of flexible pressure sensors. Nevertheless, the performance development of flexible pressure sensors is limited due to cost and process difficulty, prepared by inverted mold lithography. In this work, microstructured arrays printed by aerosol printing act as the IDL of the sensor. It is a facile way to prepare flexible pressure sensors with high performance, simplified processes, and reduced cost. Simultaneously, the effects of microstructure size, PDMS/MWCNTs film, microstructure height, and distance between the microstructures on the sensitivity and response time of the sensor are studied. When the microstructure size, height, and distance are 250 µm, 50 µm, and 400 µm, respectively, the sensor shows a sensitivity of 0.172 kPa⁻¹ with a response time of 98.2 ms and a relaxation time of 111.4 ms. Studies have proven that the microstructured dielectric layer printed by aerosol printing could replace the inverted mold technology. Additionally, applications of the designed sensor are tested, such as the finger pressing test, elbow bending test, and human squatting test, which show good performance.

Flexible pressure sensors have attracted much attention in academia owing to their wide-ranging applications in wearable electronics, medical electronics and digital health. However, practical engineering applications have been restricted because of limitations in efficiency, manufacturing costs and sensitivity. In this work, we propose an innovative method for high-efficiency printing of microstructures that replaces traditional inverted mold methods. We developed a high-sensitivity flexible piezoresistive pressure (FPP) sensor with a high manufacturing efficiency and low manufacturing cost. The sensor was encapsulated by connecting a polydimethylsiloxane film with microstructures prepared using the sandpaper-molding method, and then integrated with an interdigital electrode and spherical micro-structures fabricated via resonant printing. In this way, the manufacturing process was simplified by breaking it down into two steps. The performance of the sensor was assessed by conducting experiments under different pressure regimes. The results demonstrated ultra-high sensitivity (0.0058–0.024 kPa⁻¹) and a wide pressure detection range (1–100 kPa), spanning the entire range of pressure monitoring typically observed for vital and health signals. The response time of the sensor was less than 72 ms. Furthermore, the performance of the fabricated sensor was highly stable after 1000 bending cycle. The potential applications of the FPP sensor are discussed in area such as the human body and mouse.

Improving the conductivity of metal particle inks is a hot topic of scientific research. In this paper, a method for preparing metal-filled particles was proposed. By adding filled particles to the ink, the size distribution of particles could be changed to form a bimodal distribution structure in accordance with Horsfield’s stacking model. The filling particles had small volume and good fluidity, which could fill the gaps between the particles after printing and improve its electrical conductivity without significantly changing the metal solid content in the ink. Experimental results show that the silver content of the ink slightly increased from 15 wt% to 16.5 wt% after adding filled particles. However, the conductivity of the ink was significantly improved, and after sintering, the resistivity of the ink decreased from 70.2 μΩ∙cm to 31.2 μΩ∙cm. In addition, the filling particles prepared by this method is simple and has a high material utilization rate, which could be applied to the preparation of other kinds of metal particle inks.

Piezoresistive pressure sensors have attracted significant attention because of their application prospects in a wide range of fields, including wearable electronics, electronic skin, and robotics. In pressure testing, the material and internal structure of piezoresistive pressure sensors affect their performance. Therefore, the primary focus of this research was to evaluate the use of graphene (Gr)-incorporated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) ink for printing microstructures on flexible substrates to fabricate small piezoresistive sensing composite structures. The effect of graphene on the resulting microstructure was investigated, revealing an increase in conductivity under the same pressure. Experiments showed that incorporating graphene at 0.75 wt% and controlling the microstructure (height of 35 μm and electrode spacing of 200 μm) improved the sensitivity of the designed sensor, which exhibited a sensitivity of 0.49 kPa⁻¹, a fast response time of 42 ms, and good durability. Moreover, the sensor performed well in the detection of physiological signals, such as the human pulse and joint flexion. Therefore, it has potential application value in human health monitoring.