Sublimation of orientated amino acid films for reliable, amplified piezoelectric performance

TL;DR

This paper demonstrates that sublimation of amino acids onto conductive substrates produces uniformly oriented polycrystalline films with enhanced and consistent piezoelectric responses, overcoming previous variability issues in biomolecular piezoelectric materials.

Contribution

The study introduces a solvent-free sublimation technique to create highly oriented amino acid films with superior and reproducible piezoelectric performance, advancing biomolecular piezoelectric applications.

Findings

Maximum piezoelectric response of 9.6 pC/N in L-Valine films

Maximum voltage output of 4.6 V from sublimated films

Consistent material properties across multiple films and points

Abstract

Biomolecular crystals, such as amino acids, peptides, and proteins, have emerged as potential next generation piezoelectric materials due to their low-cost, biocompatibility, eco-friendliness, and reduced permittivity versus ceramics. However, many challenges have limited their acceleration into mainstream sensing applications. Their natural self-assembly from saturated solutions into polycrystalline films reduces their effective piezoelectric output, and results in high variability within individual samples, and across sample batches when scaled-up. Here we validate the sublimation of a variety of amino acids onto conductive substrates as an effective technique for overcoming these challenges. This solvent-free crystallisation technique results in polycrystalline films with uniformly orientated crystals, and a resulting piezoelectric response that exceeds that of single crystals. We report a maximum piezoelectric response of 9.6 pC/N in films of L-Valine, which matches the predicted single crystal response, and a maximum voltage output of 4.6 V. For L-Methionine and L-Valine sublimated films the material properties are consistent at all points on the piezoelectric films and repeatable across any number of films grown under the same conditions.