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Text|Melon juice orange long Dr
Editor|Melon juice orange long Dr
introduction
It further significantly improves the triboelectric output of CNC/PHB-based TENG, which has a voltage output and current output that is 5.7 times and 12.5 times higher than the original PHB-based TENG, respectively.
Bio TENG exhibited admirable signal stability over 20,000 cycles, and despite the high hardness of CNC/PHB, a soft arch sensor with a simple structure was successfully assembled using CNC/PHB-based TENG.
New advances in biodegradable triboelectric generators
Green self-powered equipment based on biodegradable materials has attracted widespread attention, and the construction of transient bio-triboelectric generators using green internal nano-bio-triboelectric generators is proposed.
The green internal nano biotriboelectric generator is prepared from cellulose nanocrystals/polyhydroxybutyrate, prepared by high-pressure molding method, and CNC promotes the degradation of CNC/PHB and enhances the dielectric constant of CNC/PHB.
It further significantly improves the triboelectric output of CNC/PHB-based TENG, which has a voltage output and current output of 5.7 times and 12.5 times that of the original PHB-based TENG, respectively.
Over 20,000 cycles, bio-TENG exhibits admirable signal stability, despite the high hardness of CNC/PHB.
However, a soft but simple arch sensor with simple structure was successfully assembled using CNC/PHB-based TENG, which can achieve accurate real-time monitoring of various human movements.
Self-feeding systems can convert various environmental energy into electrical energy to maintain the operation of equipment, and this technology mainly relies on special coupling effects, including triboelectric, piezoelectric, electromagnetic, thermoelectric and pyroelectric effects.
A flexible piezoelectric enhanced triboelectric nanogenerator that can harvest ambient energy to drive commercial electronics is conceived to fabricate a biodegradable pressure sensor for cardiovascular postoperative care based on the triboelectric effect.
The biocompatibility and renewability of naturally biodegradable materials allow these materials to be used in TENG for implantable medical functional devices, transient medical devices, and wearable sensors.
The use of biomaterials in self-powered electronics and systems has great potential and value, and most biomaterials often have structural or functional deficiencies, and multifunctional chemical or physical methods are necessary to address these issues.
Research and innovation of earth-friendly self-energy technology of polyhydroxybutyrate composites
Polyhydroxybutyrate is a thermoplastic chiral polyester, which is synthesized by microorganisms as a carbon source and energy storage in the case of carbon and nitrogen nutritional imbalance, and PHB has good environmental adaptability and biodegradability.
Its decomposition products can be safely absorbed by the environment, and microbial polyesters also have some special functions, including piezoelectric properties and pyroelectric properties, about which have been reported and applied.
PHB/rGO3D composite biological scaffolds for various tissue engineering were prepared by electrospinning technology, and Zviagin et al. fabricated fiber scaffolds with ZnO/PHB.
Improved piezoelectric response of scaffolds, these applications involve only bioengineering, and as far as is known, there are few reports of PHBs in green self-powered plants.
Cellulose is a biopolymer produced on Earth from a wide range of sources, and one-dimensional cellulose nanocrystals with high crystallinity and a diameter of less than 100 nanometers can be prepared by chemical, physical or biological treatment.
Natural CNC has a highly ordered crystalline structure, large specific surface area, unique morphological structure, good environmental adaptability and strong hydrophilicity, so far, CNC has been applied to many advanced applications.
Such as supercapacitors, batteries, sensors, etc., it is considered an attractive component for manufacturing functional materials, and the combination of CNC and PHB may trigger new properties or improve existing ones.
For the first time, a green internal nano-biological triboelectric generator based on a green internal nano bio-triboelectric generator was prepared, and a flexible bio-TENG sensor composed of a high-hardness bio-sourced CNC/PHB composite material was further fabricated.
Green nanopacking CNC has a considerable impact on the degradation and dielectric properties of green PHB, and CNC/PHB with higher dielectric constant can induce more charge on the back electrode, thereby greatly improving the performance of biological TENG.
TENG exhibits remarkable stability of electrical signals over 20,000 cycles, and a simple but flexible biological TENG sensor is designed and assembled based on the triboelectric effect of CNC/PHB bio-nanocomposites.
Used to collect information about human movements, this further demonstrates the considerable value of CNC/PHB biocomposites in environmentally friendly self-powered sensors.
The dispersion and morphology of CNC in water and 5CNC/PHB casting film are directly revealed by transmission electron microscopy, CNC has good dispersion in water, and the length and diameter of CNC are about 200 nm and 10 nm.
The morphology and structure of the CNC did not change in the prepared CNC/PHB composite samples, and most importantly, the green dopant achieved relatively good dispersion in the PHB matrix.
To investigate the effect of CNC on the crystal structure of PHB, further characterization was carried out, showing DSC and WAXD results of CNC/PHB nanocomposites, showing melting behavior and information about the crystalline region.
For the original PHB sample, its crystallinity is 76.0%, and when 1% CNC is added, the green internal nano biotriboelectric generator has a higher crystallinity of 78.0%, with a further increase in CNC content.
The crystallinity of CNC/PHB nanocomposites decreased from 78.0% to 75.4%, and it is generally believed that the crystallization of polymers can be divided into two stages: nucleation and growth.
Moderate levels of CNC as nucleating agents are beneficial for the formation of anisotropic structures, but too much CNC may hinder the entry of polymer molecular chains into the crystal lattice.
A similar phenomenon occurs in the crystallization process of PDLA/PLLA/CQD composites, and WAXD is further used to examine the microstructure of PHB crystals in CNC/PHB.
The three CNC/PHB samples had similar X-ray diffraction spectra, suggesting that they may have similar crystalline structures, and the crystal morphology of the 3CNC/PHB samples was directly observed by SEM.
In addition to these structural characterizations, degradation of biomaterials is discussed, with pure PHB with little mass loss in alkaline aqueous solution and no significant change in appearance, compared to PHB samples.
The remaining mass fraction of the 5CNC/PHB composites decreased over time, indicating that the biocomposites underwent a hydrolysis reaction, and when the degradation time reached 29 days, the sample edges turned white and cracks appeared on the sample surface.
The white area expanded, the sample broke down into pieces within 116 days, and after another 60 days, the remaining mass fraction of the 5CNC/PHB sample reached about 84%.
Compared with pure PHB almost non-degradation, the almost no degradation of 5CNC/PHB may be attributed to the following three points, the tight structure in the crystalline region makes the penetration of the solution difficult, and the pure PHB sample has a higher crystallinity and is more harmful to hydrolytic degradation.
CNC, a hydrophilic nanomaterial, improves the hydrophilicity of CNC/PHB nanocomposites, which further facilitates solution diffusion and hydrolysis reactions in CNC/PHB, last but not least.
The lower experimental temperature inhibited the hydrolysis reaction of PHB and CNC/PHB, which confirmed the great possibility and value of green internal nanobiocomposites in the field of degradable electronic devices.
CNC/PHB composites with different CNC content are assembled into TENG, and since the surface potential of CNC/PHB is different from that of polydimethylsiloxane, a friction potential is established when the two materials come into contact and then separate.
It can drive the reciprocating flow of electrons between the back electrode and the ground, and the pure PHB-based TENG was prepared using the same method as a reference to evaluate the kinetic energy harvesting performance of the generator.
The electrical output of bio-TENG under external excitation shows the electrical output of bio-TENG under external excitation of 4N and 1Hz, and the power generation energy of CNC/PHB-based TENG increases with the increase of CNC content.
The open-circuit voltage and short-circuit current of 5CNC/PHB-based TENG can reach 248.8 V/cm3 and 2.5 μA/cm3, respectively, which are 6.7 times and 13.5 times that of pure PHB-based TENG, respectively, because these composites have a similar appearance and internal structure.
Research and innovation in sustainable energy applications of biodegradable nano-biotriboelectric power generation technology
"where Voc is the open-circuit voltage, Qsc is the short-circuit transmitted charge, σ1 is the surface charge density on the back electrode, S is the surface area of the electrode, and C is the capacitance between the back electrode and the ground terminal, when the test conditions remain unchanged.
S and C are usually constants, Voc and Qsc are only related to σ1, and for CNC/PHB with a higher dielectric constant, it can cause more charge on the back electrode.
And thus improve Voc and Qsc, because the short-circuit current is defined as the ratio of Qsc to time, so Isc also increases with the amount of CNC.
A detailed study of the 5CNC/PHB-based TENG also determined the effect of the excitation frequency and force amplitude on the triboelectric output, and the electrical output of the 5CNC/PHB-based TENG is collected at different applied forces of 1Hz at a given frequency.
The open-circuit voltage and short-circuit current output gradually increased with the increase of the impact force, and the voltage and current output density increased from 248.8 V/cm3 and 2.5 μA/cm3 to 331.4 V/cm3 and 4.9 μA/cm3.
These results show that the 5CNC/PHB-based TENG is relatively sensitive to changes in external applied forces, thus proving that this green generator can convert a variety of environmental mechanical energy into electrical energy.
The electrical output of a 5CNC/PHB-based TENG stimulated by a 16N impact force varies in frequency from 1 Hz, 2 Hz to 3 Hz, similarly, as the excitation frequency increases, the biological TENG can produce a higher electrical output.
Voltage densities of 365.2 V/cm3 and current densities of 5.5 μA/cm3 can be obtained in relatively small increments, similar phenomena have been observed in previous studies.
This biomaterial nanogenerator can respond to changes in stress and frequency, suggesting that this triboelectric mechanical energy conversion device can adapt to mechanical movements in a variety of environments.
More research was also done on electrical output performance, and in order to determine the maximum electrical power output, the current and voltage of 5CNC/PHB-based TENG under different external resistors were collected.
Current and voltage are positively and negatively correlated with the external load resistance because of the ohmic loss, which changes drastically when the resistance changes from 1 MΩ to 5 GΩ.
The dependence of instantaneous power density on external load resistance is calculated, and when the external resistance reaches about 166 MΩ, the instantaneous peak power is maximum, and the corresponding electrical power density is about 58.4 μW/cm3.
A range of capacitors charged by 5CNC/PHB-based TENG is shown, with 0.1 μF and 0.2 μF capacitors charging to 3 V in approximately 50 s and 100 s, respectively.
Stable energy output is one of the important criteria for evaluating the performance of electronic devices, and the short-circuit current of 5CNC/PHB-based TENG under continuous excitation was selected as the main criterion.
The current generated by the device barely changes over 20,000 cycles, demonstrating the great potential of the device in the field of self-powered sensors.
Previous tests have demonstrated that 5CNC/PHB-based TENG has considerable energy output properties, and PHB materials are often highly brittle, which limits the value of biopolyesters.
A small, flexible sensor based on CNC/PHB was conceived that can accurately sense human movement based on the electrical signal from the sensor, and use PI as a support material to carry 5CNC/PHB samples and PDMS films.
A digital picture of the sensor is shown, which is moderately sized enough to attach to the joints of the limb, and the charge on the friction surface can create an electrostatic potential between the 5CNC/PHB sample and the ground.
To balance the resulting potential drop, electrons are driven back and forth between the back electrode and the earth, and the angle of rotation of the joint can affect the stress exerted on the arch, allowing the sensor to produce different electrical signals.
The movement of volunteers can be analyzed and sensed, and when the sensor is attached to the finger joint or elbow, the sensor can produce characteristic signals for joint movement, and the signal triggered by the bending-stretching movement has been marked with a blue dotted ellipse box.
There is a positive correlation between the sensor's signal and the angle of rotation of the joint, and the sensor is also placed in the shoe to demonstrate the versatility of the sensor.
The sensor output signal generated by the volunteers at different walking speeds, and the amplitude of the signal expands as the volunteer's speed increases.
summary
Over more than 20,000 consecutive cycles, it demonstrated significant stability and durability of the output electrical signal, and despite the high hardness of the CNC/PHB composite, a flexible but simple arched sensor was fabricated using CNC/PHB-based bio-TENG.
It has important practical value in motion monitoring, and it is believed that this work confirms a simple and effective way to improve the output performance of biopolyester-based TENG.
Future research efforts will mainly focus on the design and manufacture of green bionanocomposites in green with extremely high content of uniformly dispersed CNC.