O Artigo da Semana
Ismael Domingos
PhD Student (Organic Electronics, INESC MN)
Topic: Flexible triboelectric nanogenerators for a self-charging system in mobile electronics
Printed graphene electrodes for textile-embedded triboelectric nanogenerators for biomechanical sensing (link)
Abstract
Textile triboelectric nano-generators (TENGs) are emerging as a promising solution for wearable self-powered sensing technology. However, achieving textile TENGs with excellent output performance in conformable devices, while using textile compatible techniques, is still a challenge. In this work, a highly efficient flexible triboelectric textile is developed by using printed graphene electrodes with polydimethylsiloxane (PDMS) and the textile itself as the triboelectric pair. To achieve this, a textile planarization technique with a polyurethane adhesive was employed, along with three different deposition methods: graphene droplet films (GDF), graphene immersion films (GIF), and graphene spray films (GSF). The result was a flexible textile electrode that surpassed non-planarized devices in all three printing techniques, with a 4-fold improvement and a power density of 3.08 µW/cm². Moreover, by increasing the TENG contact area through the use of four parallel devices measuring 3 × 3 cm² each, the power output reached an effective power of 60 µW. The flexible TENG presents a stable output performance under strong deformation and its sensitivity to movement was explored as wearable sensor to monitor biomechanical movements. This work provides a versatile method for constructing flexible triboelectric textile fabrics using only industrial compatible printing textile processes, paving the way to the seamless integration of self-powered wearable sensing technology into textiles.
Daniela Pereira
PhD Student (Wide Bandgap Semiconductors, INESC MN e CTN )
Topic: Defect engineered 2D oxide field effect transistors for efficient biosensing
Engineering strain and conductivity of MoO3 by ion implantation (link)
Abstract
α-MoO3 lamellar crystals are implanted with 170 keV oxygen ions at room temperature and with fluences between 1 × 1012 cm^−2 and 1 × 1017 cm^−2, in order to modify the electrical and structural properties of the crystals. A controllable and significant increase of the electrical conductivity, over several orders of magnitude, is observed after implantation at high fluences. Based on high resolution X-ray diffraction (HRXRD) and micro-Raman spectroscopy measurements, this effect is attributed to the formation of donor-type defect complexes and new phases more conductive than the α-MoO3 orthorhombic phase. A significant expansion of the b lattice parameter, increasing with fluence, is observed as a response to the defects created by implantation. Strain build-up occurs in several steps and in distinct depth regions within the implanted layer. Contrary to the typical values reported for other implanted oxide materials, an unusually high maximum perpendicular deformation of ∼3 % is verified.