Customer Success Stories | Nature Materials: Inspired by lotus leaves, ultra sensitive pressure sensors can be used for wireless intracranial pressure monitoring and laparoscopic surgery

National University of Singaporecorresponding authorDr. Benjamin C. K. Teewait forsomeone,Taking inspiration from the gas encapsulation phenomenon on the surface of lotus leaves, a pressure sensor was designed that can modulate pressure by changing capacitance at the solid-liquid liquid gas multiphase interface and elastic gas layer. This sensor is composed ofNanoscribebased onPrinciple of two-photon polymerizationProduction of PPGT2 micro nano processing system.This manufacturing method reduces friction and achieves almost frictionless contact line movement, thereby realizing Zhuoyue's pressure sensing performance. The sensor demonstrated its functionality under challenging conditions, including turbulent flow, in vivo biological environment, and laparoscopic surgery.

The related paper is titled "Fractional Multiphasic Interface for Near Ideal Aero Elastic Pressure Sensing" and was published inNature materialsIn the journal. The co first author is from the National University of SingaporeWen Cheng, Xinyu WangThe Shanghai University of Science and TechnologyDr. Xiong Ze.

Verify the influence of microstructure design on sensor repeatability

The research aims to develop a new type of pressure sensor called eAir, inspired by the water air interface phenomenon on the non wetted surface of lotus leaves. Unlike traditional solid-state pressure sensors, researchers have achieved non fixed contact line motion in a multi-scale structured solid-liquid gas-liquid multiphase system through Nanoscribe two-photon aggregation technology, creating a new type of flying elastic capacitive pressure sensor. Using the Nepenthes nilotica plant as a model, a micro (~0.5 mm3) sensor was fabricated using a hexagonal wall shaped column array microstructure. The surface of the pillar is designed as a working electrode, and by injecting lubricant into the conductive nanostructure, it becomes super smooth. Under different liquid pressures, the liquid can wet/dehumidify the column electrode without causing contact angle hysteresis. This process changes the contact area between the liquid and electrode, thereby altering the capacitance. Compared with other pressure sensors operating in liquid environments, these sensors can measure small pressure fluctuations in liquids, with ultra-low hysteresis (1.34 ± 0.20%), high sensitivity (79.1 ± 4.3 pF kPa ^ -1), and high linearity (R2=0.99944 ± 0.00015); The nonlinearity is 1.49 ± 0.17%.

Figure 1 Concept and design of eAir. a、 Schematic diagram of the water air interface on the non wetted surface of lotus leaves. Gas is trapped between structures below the liquid gas interface. As the water pressure changes, the interface moves up and down. b、 The pressure sensing response of sensors made from lotus leaves. c. Schematic diagram of eAir design. The surface of the column is used as a working electrode and inspired by the vine plant, by injecting lubricant into the conductive nanostructure, it becomes super smooth. Liquids can wet/dehumidify column electrodes at different liquid pressures without causing contact angle hysteresis. This process changes the contact area between the liquid and electrode, thereby altering the capacitance. Illustration: Equivalent circuit of eAir. Ccounter， Electric double-layer capacitance at the liquid electrode interface; CEDL.ct， Electric double-layer capacitance at the interface of liquid working electrode coating; Cd.ct， The dielectric capacitance between the working electrode and the surface coating liquid interface; Cd+air， The capacitance between the working electrode and the liquid is conducted through gas; C0， Interface capacitance of inactive regions. d. EAir's pressure sensing response. e. A schematic diagram of the capacitor composition of eAir devices, as well as surfaces labeled I-IV, which have different wetting properties and are used to adjust the performance of sensors. The label (on the left) corresponds to the illustration in c. Δθ， The contact angle of the surface lags behind. As the surface roughness decreases from IV to I, Δ θ also decreases, indicating a transition from strong adhesion to frictionless sliding of liquids. The changes in these surface properties affect the performance of the sensor. f、 Schematic diagrams of forward/reverse threshold performance for non ideal pressure sensors, as well as linear and hysteresis free performance diagrams for ideal pressure sensors. g、 Comparison of linear performance with reported liquid environmental pressure sensors. To highlight the differences, linearity (1/(1-R2)) was defined for comparison. R2 (coefficient of determination) is the value of the linear fitting result of the corresponding equipment performance curve: the higher the linearity, the better the linearity.

Verify the impact of interface wetting performance on sensor performance

The four different surfaces designed in the study are labeled as I to IV. By adjusting the surface roughness and energy, these surfaces have different contact angles and contact angle hysteresis. Researchers have found that different surface treatments can lead to varying degrees of fixation of the contact line on the liquid surface, thereby affecting the numerical values of the advancing angle and contact angle hysteresis. In cases with high surface roughness, such as surfaces III and IV, the presence of polyaniline (PAni) nanowires significantly enhances the fixation of contact wires. Meanwhile, these surfaces may develop under liquid pressureBorn notReversible transformationTransformation leads to an increase in the forward angle and contact angle lag after applying pressure. The Nanoscribe two-photon micro nano processing system can achieve surface roughness reduction to the nanoscale. In experiments such as surface II, the lag of the advancing angle and contact angle will also decrease accordingly. On surface I, by applying silicone oil, the surface becomes very smooth, similar to a smooth liquid penetrating the porous surface. This leads to a reduction in the fixation of the contact wire and a decrease in the forward angleThe contact angle hysteresis can be almost ignored.The researchers also observed that different interface wetting characteristics directly affect the performance of the sensor. Specifically, the larger the forward angle, the higher the forward threshold of the sensor; The larger the contact angle hysteresis, the higher the reverse threshold and hysteresis performance of the sensor. These results provide guidance for optimizing sensor performance.

Nanoscribe's newly launched Quantum X series platform system features grayscale lithography technology (2GL) ®)， It can achieve high design freedom, high-speed printing efficiency, and high precision required for additive manufacturing of complex structures with ultra smooth surfaces. The fast and accurate additive manufacturing process greatly shortens the design iteration cycle. The Quantum X shape is a truly versatile model. Based on two-photon aggregation technology, this laser direct writing system is not only the best model for rapid prototyping, but also suitable for large-scale production of 2.5D and 3D shapes with any sub micron precision on the wafer. The high precision of the new Quantum X shape relies on its highest voxel modulation ratio and ultra-fine processing mesh, enabling sub voxel size control. In addition, benefiting from the fine tuning of voxels by two-photon grayscale lithography, the system can achieve ultra smooth surface microstructure fabrication while maintaining high-precision shape control. Quantum X shape is not only applied in biomedical, micro optics MEMS、 The ideal tool for rapid prototyping of devices in microchannels, surface engineering, and many other fields has also become a simple tool for mass production of small structural units based on wafers.

More information about 3D two-photon maskless lithography technology and product consultation

Welcome to contact Nanoscribe China Branch - Nano 3D Technology (Shanghai) Co., Ltd

German Nanoscribe ultra-high precision two-photon micro nano 3D maskless lithography system:

Photonic Professional GT2 Two Photon Micro Nano 3D Maskless Lithography System

Quantum X Align Two Photon Nano Automatic Alignment System

Quantum X shape two-photon high-performance 3D micro nano machining system

bio X quantity Two photon high-precision 3D bioprinting system