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Self-assembly of diphenylalanine peptide with controlled polarization for power generation

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ABSTRACT

Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V−1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm−2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

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Characterization of the FF peptide-based power generators.(a) Schematic of the FF peptide-based generator connected to the measurement equipment. Bottom-right inset: photography of a real device. (b) Schematic of the measurement set-up in which a linear motor pushes with controlled forces on the top electrode in (a). The linear motor was programmed to always keep contact with the top electrode to minimize the effect of static charges. (c,d) Open-circuit voltage (c) and short-circuit current (d) from a generator using microrods from positive-EF growth. (e) Dependence of the power output from the generators on the resistance of the external load under 50 N applied force. (f) Linear dependence of the open-circuit voltage on the applied force. Error bar: s.d.
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f3: Characterization of the FF peptide-based power generators.(a) Schematic of the FF peptide-based generator connected to the measurement equipment. Bottom-right inset: photography of a real device. (b) Schematic of the measurement set-up in which a linear motor pushes with controlled forces on the top electrode in (a). The linear motor was programmed to always keep contact with the top electrode to minimize the effect of static charges. (c,d) Open-circuit voltage (c) and short-circuit current (d) from a generator using microrods from positive-EF growth. (e) Dependence of the power output from the generators on the resistance of the external load under 50 N applied force. (f) Linear dependence of the open-circuit voltage on the applied force. Error bar: s.d.

Mentions: We investigated the power generation using FF peptide microrods with controlled polarizations. The FF peptide microrod array was sandwiched between two electrodes that connected to an external load or measuring instruments, as shown in Fig. 3a. When the device was compressed and released, FF peptide microrods converted the mechanical energy into electricity. The device characterization set-up in Fig. 3b includes a closed-loop linear motor with a load cell. A periodic compressive force was applied on the power generator for 1 s and released for 2 s (Fig. 3b). The power generation of FF peptide microrods from positive-EF growth is shown in Fig. 3c,d. Under an applied force F=60 N, the output open-circuit voltage (Voc) and short-circuit current (Isc) reached 1.4 V and 39.2 nA, respectively. FF peptide microrods from negative-EF growth produced opposite voltage and current outputs, and FF peptide microrods from no-EF growth produced much smaller output (Supplementary Fig. 5). The signs of open-circuit voltage and short-circuit current under compressing force all agree with the polarization direction measured from PFM. Reversed connection tests show that all outputs are reversed (Supplementary Fig. 6). The switching-connection test excluded the errors from the variation of contact resistance or parasitic capacitance and confirmed that the detected electrical signal was truly from the piezoelectric FF peptide microrods. Unlike generators based on virus or zinc oxide nanostructures, which showed rapid decay of the open-circuit voltage due to partially the leakage current through these materials5633, the open-circuit voltage herein remained at a constant level owing to the excellent dielectric properties of FF peptides34 (Supplementary Fig. 7). When connected to external resistors, FF peptide microrods grown with electric fields produced up to 3.3 nW cm−2 at 50 MΩ, which is 3.8 times higher than the power density of zinc oxide nanowire-based generators (0.854 nW cm−2 for a single generator) driven by a 24 times greater pressure33. Our comparison here is conservative since the reported vertical zinc oxide nanowire-based generator was not connected to a load, so its power output was estimated using separately measured peak voltage (96 mV) and current (8.9 nA cm−2), which cannot be achieved simultaneously. In contrast, FF peptide microrods grown without electric fields yield power about 5 times lower than the power produced from microrods grown with electric fields (Fig. 3e), demonstrating the importance of the applied electric field for output enhancement. The effect of strain rate on the output of FF peptide-based generators was also investigated, and increasing strain rate was found to increase the peak power output up to 7 nW cm−2 (Supplementary Fig. 5e), which was comparable to the performance of a generator based on lead zirconate titanate nanoribbons35.


Self-assembly of diphenylalanine peptide with controlled polarization for power generation
Characterization of the FF peptide-based power generators.(a) Schematic of the FF peptide-based generator connected to the measurement equipment. Bottom-right inset: photography of a real device. (b) Schematic of the measurement set-up in which a linear motor pushes with controlled forces on the top electrode in (a). The linear motor was programmed to always keep contact with the top electrode to minimize the effect of static charges. (c,d) Open-circuit voltage (c) and short-circuit current (d) from a generator using microrods from positive-EF growth. (e) Dependence of the power output from the generators on the resistance of the external load under 50 N applied force. (f) Linear dependence of the open-circuit voltage on the applied force. Error bar: s.d.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120215&req=5

f3: Characterization of the FF peptide-based power generators.(a) Schematic of the FF peptide-based generator connected to the measurement equipment. Bottom-right inset: photography of a real device. (b) Schematic of the measurement set-up in which a linear motor pushes with controlled forces on the top electrode in (a). The linear motor was programmed to always keep contact with the top electrode to minimize the effect of static charges. (c,d) Open-circuit voltage (c) and short-circuit current (d) from a generator using microrods from positive-EF growth. (e) Dependence of the power output from the generators on the resistance of the external load under 50 N applied force. (f) Linear dependence of the open-circuit voltage on the applied force. Error bar: s.d.
Mentions: We investigated the power generation using FF peptide microrods with controlled polarizations. The FF peptide microrod array was sandwiched between two electrodes that connected to an external load or measuring instruments, as shown in Fig. 3a. When the device was compressed and released, FF peptide microrods converted the mechanical energy into electricity. The device characterization set-up in Fig. 3b includes a closed-loop linear motor with a load cell. A periodic compressive force was applied on the power generator for 1 s and released for 2 s (Fig. 3b). The power generation of FF peptide microrods from positive-EF growth is shown in Fig. 3c,d. Under an applied force F=60 N, the output open-circuit voltage (Voc) and short-circuit current (Isc) reached 1.4 V and 39.2 nA, respectively. FF peptide microrods from negative-EF growth produced opposite voltage and current outputs, and FF peptide microrods from no-EF growth produced much smaller output (Supplementary Fig. 5). The signs of open-circuit voltage and short-circuit current under compressing force all agree with the polarization direction measured from PFM. Reversed connection tests show that all outputs are reversed (Supplementary Fig. 6). The switching-connection test excluded the errors from the variation of contact resistance or parasitic capacitance and confirmed that the detected electrical signal was truly from the piezoelectric FF peptide microrods. Unlike generators based on virus or zinc oxide nanostructures, which showed rapid decay of the open-circuit voltage due to partially the leakage current through these materials5633, the open-circuit voltage herein remained at a constant level owing to the excellent dielectric properties of FF peptides34 (Supplementary Fig. 7). When connected to external resistors, FF peptide microrods grown with electric fields produced up to 3.3 nW cm−2 at 50 MΩ, which is 3.8 times higher than the power density of zinc oxide nanowire-based generators (0.854 nW cm−2 for a single generator) driven by a 24 times greater pressure33. Our comparison here is conservative since the reported vertical zinc oxide nanowire-based generator was not connected to a load, so its power output was estimated using separately measured peak voltage (96 mV) and current (8.9 nA cm−2), which cannot be achieved simultaneously. In contrast, FF peptide microrods grown without electric fields yield power about 5 times lower than the power produced from microrods grown with electric fields (Fig. 3e), demonstrating the importance of the applied electric field for output enhancement. The effect of strain rate on the output of FF peptide-based generators was also investigated, and increasing strain rate was found to increase the peak power output up to 7 nW cm−2 (Supplementary Fig. 5e), which was comparable to the performance of a generator based on lead zirconate titanate nanoribbons35.

View Article: PubMed Central - PubMed

ABSTRACT

Peptides have attracted considerable attention due to their biocompatibility, functional molecular recognition and unique biological and electronic properties. The strong piezoelectricity in diphenylalanine peptide expands its technological potential as a smart material. However, its random and unswitchable polarization has been the roadblock to fulfilling its potential and hence the demonstration of a piezoelectric device remains lacking. Here we show the control of polarization with an electric field applied during the peptide self-assembly process. Uniform polarization is obtained in two opposite directions with an effective piezoelectric constant d33 reaching 17.9 pm V−1. We demonstrate the power generation with a peptide-based power generator that produces an open-circuit voltage of 1.4 V and a power density of 3.3 nW cm−2. Devices enabled by peptides with controlled piezoelectricity provide a renewable and biocompatible energy source for biomedical applications and open up a portal to the next generation of multi-functional electronics compatible with human tissue.

No MeSH data available.


Related in: MedlinePlus