Recently, flexible capacitive pressure sensors have received extensive attention in the field of wearable electronics. High sensitivity and long-term durability in a wide linear range are key requirements for manufacturing flexible pressure sensors suitable for various applications. The team of Professor Jae Yeong Park of Kwangun University in South Korea proposed a special method by fabricating a mixed ion nanofiber membrane (a sensing layer composed of MXene and lithium ion salt of lithium sulfonamide) in a polyvinyl alcohol elastomer matrix. To enhance the sensitivity and linear range of capacitive pressure sensors. (1) The reversible ion pump triggered by the hydrogen bond in the hybrid sensing layer produces high sensitivity of 5.5 and 1.5kPa-1 in a wide linear range of 0-30kPa and 30-250kPa, respectively, and a fast response time of 70.4ms . (2) In addition, even at a high pressure of 45kPa, the manufactured sensor shows a minimum detection limit of 2Pa and high durability exceeding 20,000 continuous cycles. (3) These results show that the sensor can be used in mobile medical monitoring equipment and next-generation artificial skin. The related paper is entitled "Hydrogen-Bond-Triggered Hybrid Nanofibrous Membrane-Based Wearable Pressure Sensor with Ultrahigh Sensitivity over a Broad Pressure Range" published in the top international journal ACS Nano (IF=14.588).

Figure 1. Manufacturing and structural characterization of an INM-based capacitive pressure sensor.

(A) Schematic diagram of INM manufacturing sequence.

(B) Highly magnified FESEM image of uniform fibers with a diameter of about 120 nm.

(C) Low-resolution TEM image of composite nanofibers, showing single-layer and multi-layer MXene nanosheets inside the polymer matrix.

(D) Schematic diagram of the manufactured device.

(E) Photograph of the finished sensor device.

Figure 2. The molecular structure and working principle of an INM-based pressure sensor.

(A) Schematic diagram of the hydrogen bond interaction between MXene functional groups (-OH, -F and -O) and LS species.

(B) A schematic diagram describing the working principle of INM-based sensors before and after pressure is applied.

(D) COMSOL simulation of the sensor surface stress distribution obtained under different pressure conditions.

(E) Von-Mises stress is a function of the deformation of the sensing layer.





Figure 3. Electromechanical characteristics of INM-based pressure sensors.







Figure 4. The practical application of pressure sensors based on INM in the low to medium pressure range.





Figure 5. Application of prefabricated pressure sensor in high pressure range.

(A) A schematic diagram of a pressure sensor array (5×5 pixels) made by sandwiching the INM and the pattern electrode.

(B-d) A photo of the pressure sensor array, with different 3D printed models placed on its surface to detect the applied pressure and the corresponding contour map of the spatial pressure distribution.

Literature link:

https://doi.org/10.1021/acsnano.0c07847


Information source: scientific research

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