Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.

Peptide assemblies are ideal components for eco-friendly optoelectronic energy harvesting devices due to their intrinsic biocompatibility, ease of fabrication, and flexible functionalization. However, to date, their practical applications have been limited due to the difficulty in obtaining stable, high-performance devices. Here, it is shown that the tryptophan-based simplest peptide cycloglycine-tryptophan (cyclo-GW) forms mechanically robust (elastic modulus up to 24.0 GPa) and thermally stable up to 370 °C monoclinic crystals, due to a supramolecular packing combining dense parallel β-sheet hydrogen bonding and herringbone edge-to-face aromatic interactions. The directional and extensive driving forces further confer unique optical properties, including aggregation-induced blue emission and unusual stable photo-luminescence. Moreover, the crystals produce a high and sustained opencircuit voltage (1.2 V) due to a high piezoelectric coefficient of 14.1 pC N−1. These findings demonstrate the feasibility of utilizing self-assembling peptides for fabrication of biointegrated microdevices that combine high structural stability, tailored optoelectronics, and significant energy harvesting properties.

Classical Grand Canonical Monte Carlo (GCMC), classical molecular dynamics (MD), and density functional theory (DFT) have been employed to study the effect of pore-size and pore-chemistry on the adsorption of carbon dioxide in the SIFSIX-3-M family of hybrid ultramicroporous materials (HUMs), where M = Zn2+, Ni2+, or Cu2+. These HUMs have been shown to exhibit exceptional affinity toward small polarizable molecules such as CO2, and our simulated isotherms are in good agreement with those obtained experimentally. Isosteric heats of adsorption (Q st) calculated using these theoretical methods also follow the experimentally observed trend, decreasing as M varies from Cu to Ni to Zn in SIFSIX-3-M. More specifically, the interaction energy between a CO2 molecule and HUMs with varying pore-size was calculated using a DFT-D2 level of theory. The strongest interaction energy was calculated for SIFSIX-3-Cu (56.89 kJ mol–1) where the pore-size is the smallest. The interaction energy decreased in SIFSIX-3-Ni (52.21 kJ mol–1) and SIFSIX-3-Zn (48.46 kJ mol–1), each of which exhibiting larger pore dimensions. The increase in the strength of the interaction in SIFSIX-3-Cu is attributed to the shorter distance between the negatively charged equatorial fluorine atoms of the SiF6 2– pillar and the positively charged carbon atom of CO2. Finally, DFT-D2 calculations were used to reconcile the uncertainty in locating the exact crystallographic position of equatorial fluorine atoms in the SIFSIX-3-M family. The calculated interaction energies agree best with experimental Q st values when equatorial fluorine atoms are at a 45° angle with respect to the crystallographic a-axis. Our theoretical calculations thus create a foundation for first-principles based rational design of SIFSIX-3-M and other HUMs for selective adsorption of carbon dioxide and other relevant sorbates such as acetylene.

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Diphenylalanine (FF) demonstrates a robust ability to self‐assemble at the nanoscale forming a variety of structures ranging from nanospheres to nano‐ and microtubes resulting in outstanding functional properties including pyro‐ and piezoelectricity. FF nanotubes mimic the structure of β‐amyloid fibrils characteristic of Alzheimer's disease and thus can serve as a model material in biology and medicine. In this work, we report experimental proof that water trapped inside nanotubes exhibits dielectric properties similar to that of bulk water despite being confined in an ∼1 nm internal cavity. FF peptides thus provide a suitable template for the stabilization of the tetrahedral configuration of bulk water. Several phase transitions were observed via broadband dielectric spectroscopy and differential scanning calorimetry. Of these, two glass transitions at 205 K and 133 K related to different phases of water were found. The presence of α‐relaxation in the so‐called “no man's land” leads to a global glass transition at Tg = 133 K and structural phase transition at 230 K characteristic of tetrahedral water. The characterized collective response of water dipoles to an external electric field renders high pyro‐ and piezoelectric activity and non‐linear optical effects in FF dipeptides, conferring polarization‐dependent functionality to this important class of biomaterials.

Mobile phones have become an indispensable utility to modern society, with international use increasing dramatically each year. The GSM signal operates at 900MHz, 1800MHz and 2250MHz, may potentially cause harm to human tissue. Yet there is no in silico model to aid design these devices to protect from causing potential thermal effect. Here we present a model of sources of heating in a mobile phone device with experimental verification during the phone call. We have developed this mobile phone thermal model using first principles on COMSOL® Multiphysics modelling platform to simulate heating effect in human auricle region due to mobile phone use. In particular, our model considered both radiative and non-radiative heating from components such as the lithium ion battery, CPU circuitry and the antenna. The model showed the distribution and effect of the heating effect due to mobile phone use and considered impact of battery discharge rate, battery capacity, battery cathode material, biological tissue distance, antenna radio-wave frequency and intensity. Furthermore, the lithium ion battery heating was validated during experiments using temperature sensors with an excellent agreement between simulated and experimental data (<1% variation). Mobile phone heating during a typical call has also been simulated and compared with experimental infrared thermographic imaging. Importantly, we found that 1800MHz frequency of data transmission showed the highest temperature increase in the fat/water phantom used in this simulation. We also successfully compared heating distribution in human auricle region during mobile phone use with clinical thermographic images with reasonable qualitative and quantitative agreements. In summary, our model provides a foundation to conceive thermal and other physical effects caused by mobile phone use and allow for the understanding of potential negative health effects thus supporting and promoting personalized and preventive medicine using thermography.

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