In a study published in the journal NanoenergyA highly sensitive hybridized manometer based on nanofibers and membranes has been introduced to eliminate the limitations of the current piezoresistive manometer by increasing the operating range and sensitivity.
Research: Piezoresistive sensor based on nanofibrous membrane, developed using polyaniline nanospins, for high-performance electronic skins. Image Credit: HQuality / Shutterstock.com
What are wearable electronic skins?
Extensive study of the creation of electronic skin technology (e-skin) has greatly expanded people’s understanding of individual health care systems.
Elastic e-skin can be made to resemble actual skin, allowing you to constantly non-invasively monitor physiological data to maintain optimal health. This simulation at the design stage is usually performed at the component level, for example, using soft polymers for the substrate material, such as leather, adjusting nanoscale frames in the touch layer to enhance touch response and a microcontroller with a wireless component to transmit and analyze data such as sensor nervous system.
In the run-up to the COVID-19 pandemic e-skin pandemic intends to provide an alternative to the health care model through individual home diagnostics, as well as reduce hospital overcrowding. As a result, a number of approaches to the implementation of this concept have been proposed.
In particular, flexible electronic leather for tactile use has aroused great interest because of its scalability, simplicity and minimal power consumption, as well as ease of incorporation into the microprocessing unit.
On the other hand, maintaining good sensitivity even under high pressure remains a serious difficulty.
Important considerations for developing effective electronic skins
The ability to maintain good sensitivity over a wide range of operating pressures is an important criterion for the successful operation of e-skin in many situations (from modest to severe body displacement).
Sensor performance (e.g., linearity and sensitivity) is often adjusted primarily in two areas: material selection for sensor components and micro / nanoscale frames.
Taking these factors into account, the researchers sought to construct micro- / nanoscale structures, including sea urchin-like microstructures, multilayer microdome, spikes, micropyramids, hollow sphere morphology, wrinkled sheets, and multilayer nanofiber skin matrices for nanofibers. . However, each design has its pros and cons.
A critical criterion for good linearity and sensitivity of a piezoresistive detector is low starting current and significant current variation when applying pressure.
In particular, the coarse-textured sensor layer improves the response in the lower pressure area by allowing coarse interaction between the electrodes and the sensor layer.
In addition, to increase the linearity, the sensor layer needs large and constant impedance fluctuations with increasing deformation, as well as a wide range of pressure sensations. Given these challenges, the adoption of a hypersensitive spike-like structure and highly compressible membranes based on electrospinning fibers helps increase responsiveness and linearity when using e-skin.
The hybridized nanofiber films in this study were made of cellulose, polyacrylonitrile (PAN) and MXene (PCM), with cellulose and MXene acting as reinforcing materials in PAN nanofibers.
Carbonated PCM (CPCM) film was produced to achieve conductivity before PANI nanospins were applied to the film. The inclusion of PANI nanospins on the CPCM nanofiber film (P-CPCM) resulted in a larger surface strength region and greater dispersion in the contact and impedance region, in contrast to the other microstructures listed above, which greatly improved pressure sensitivity.
Characteristic features of fabricated electronic leather
The team has developed a flexible piezoresistive manometer with an extremely high response speed over a wide operating pressure range.
The improved sensor, which was centered around PANI nanoships applied to a multilayer fiber frame, demonstrated very good sensitivity across the wide linear band up to 50 kPa.
The results of this investigation showed that the geometry of the nanofibers throughout the nanofiber layer created much greater variance in contact and impedance than many documented microstructures, which most enhances responsiveness and linearity.
Moreover, due to its increased compressibility, nanofibre films with electrospinning provided good linearity and a wide range of detection. Notably, these properties allowed the detector to monitor a wide range of physiological data produced by the human body; like breathing, heart rate, wrist pulse, JVP and phonation.
A wireless setup (with Bluetooth, microprocessor, and signal conditioning circuitry) was also created to stream the detected information to a digital application for continuous real-time data tracking.
Using personal diagnostics, we believe that the flexible pressure detector based on P-CPCM nanofiber can be an effective and useful portable medical equipment as well as an alternative to the hospital care system.
Sharma, S., Chhetry, A., et al. (2022). Piezoresistive sensor based on nanofibrous membrane, developed using polyaniline nanospins, for high-performance electronic skins. Nano Energy, 95. Available at: https://www.sciencedirect.com/science/article/pii/S2211285522000556?via%3Dihub