TIC250 - Artículoshttps://hdl.handle.net/10481/520882024-03-29T04:38:55Z2024-03-29T04:38:55ZCost-Effective PEDOT:PSS Temperature Sensors Inkjetted on a Bendable Substrate by a Consumer PrinterRivadeneyra Torres, AlmudenaFernández-Salmerón, Joséhttps://hdl.handle.net/10481/619032021-06-15T13:27:21ZCost-Effective PEDOT:PSS Temperature Sensors Inkjetted on a Bendable Substrate by a Consumer Printer
Rivadeneyra Torres, Almudena; Fernández-Salmerón, José
In this work, we report on a fabrication protocol to produce fully inkjet-printed temperature sensors on a bendable polyethylene terephthalate (PET) substrate. The sensing layer is made of polymer-based Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) ink that is electrically contacted by an underlying interdigitated electrode (IDE) structure based on a silver nanoparticle (AgNP) ink. Both inks are available commercially, and no further ink processing is needed to print them using a cost-effective consumer printer with standard cartridges. The fabricated sensor modules are tested for different IDE dimensions and post-deposition treatments of the AgNP film for their response to a temperature range of 20 to 70 °C and moisture range of 20 to 90% RH (relative humidity). Attributed to the higher initial resistance, sensor modules with a larger electrode spacing of 200 µm show a higher thermal sensitivity that is increased by a factor of 1.8 to 2.2 when compared to sensor modules with a 150 µm-spacing. In all cases, the sensors exhibit high linearity towards temperature and a response comparable to state of the art.
Laser-Fabricated Reduced Graphene Oxide MemristorsRomero Maldonado, Francisco JavierToral López, AlejandroOhata, AkikoMorales Santos, Diego PedroGarcía Ruiz, Francisco JavierGodoy Medina, AndrésRodríguez Santiago, Noelhttps://hdl.handle.net/10481/618652021-06-22T08:54:29ZLaser-Fabricated Reduced Graphene Oxide Memristors
Romero Maldonado, Francisco Javier; Toral López, Alejandro; Ohata, Akiko; Morales Santos, Diego Pedro; García Ruiz, Francisco Javier; Godoy Medina, Andrés; Rodríguez Santiago, Noel
Finding an inexpensive and scalable method for the mass production of memristors will be one of the key aspects for their implementation in end-user computing applications. Herein, we report pioneering research on the fabrication of laser-lithographed graphene oxide memristors. The devices have been surface-fabricated through a graphene oxide coating on a polyethylene terephthalate substrate followed by a localized laser-assisted photo-thermal partial reduction. When the laser fluence is appropriately tuned during the fabrication process, the devices present a characteristic pinched closed-loop in the current-voltage relation revealing the unique fingerprint of the memristive hysteresis. Combined structural and electrical experiments have been conducted to characterize the raw material and the devices that aim to establish a path for optimization. Electrical measurements have demonstrated a clear distinction between the resistive states, as well as stable memory performance, indicating the potential of laser-fabricated graphene oxide memristors in resistive switching applications.
Fabrication and Characterization of Humidity Sensors Based on Graphene Oxide–PEDOT:PSS Composites on a Flexible SubstrateRomero Maldonado, Francisco JavierRivadeneyra Torres, AlmudenaBecherer, MarkusMorales Santos, Diego PedroRodríguez Santiago, Noelhttps://hdl.handle.net/10481/612252021-06-22T08:54:29ZFabrication and Characterization of Humidity Sensors Based on Graphene Oxide–PEDOT:PSS Composites on a Flexible Substrate
Romero Maldonado, Francisco Javier; Rivadeneyra Torres, Almudena; Becherer, Markus; Morales Santos, Diego Pedro; Rodríguez Santiago, Noel
In this paper, we present a simple, fast, and cost-effective method for the large-scale fabrication of high-sensitivity humidity sensors on flexible substrates. These sensors consist of a micro screen-printed capacitive structure upon which a sensitive layer is deposited. We studied two different structures and three different sensing materials by modifying the concentration of poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) in a graphene oxide (GO) solution. The results show that the aggregation of the PEDOT:PSS to the GO can modify its electrical properties, boosting the performance of the capacitive sensors in terms of both resistive losses and sensitivity to relative humidity (RH) changes. Thus, in an area less than 30 mm2, the GO/PEDOT:PSS-based sensors can achieve a sensitivity much higher (1.22 nF/%RH at 1 kHz) than other similar sensors presented in the literature which, together with their good thermal stability, time response, and performance over bending, demonstrates that the manufacturing approach described in this work paves the way for the mass production of flexible humidity sensors in an inexpensive way.
Supplementary Materials
The following are available online at https://www.mdpi.com/2072-666X/11/2/148/s1, Figure S1: Actual view of one of the flexible RH sensors presented in this work, Figure S2: Absolute value of the impedance as a function of the relative humidity measured at different frequencies for both layout 1 (10 kHz (a) and 100 kHz (c)) and layout 2 (10 kHz (b) and 100 kHz (d)) using GO and the hybrid GO/PEDOT:PSS composites as sensitive layers, Figure S3: Equivalent parallel resistance and capacitance for layout 1 (W = 115 µm, i = 225 µm) at different frequencies using GO and the hybrid GO/PEDOT:PSS composites as sensitive layers, Figure S4: Sensitivity as a function of the frequency for the two layouts considered in this work as well as the three different sensitive layer.
Over-Stretching Tolerant Conductors on Rubber Films by Inkjet-Printing Silver Nanoparticles for WearablesAlbrecht, AndreasBobinger, MarcoSalmerón, José F.Becherer, MarkusCheng, GordonLugli, PaoloRivadeneyra Torres, Almudenahttps://hdl.handle.net/10481/555742021-06-15T13:27:22ZOver-Stretching Tolerant Conductors on Rubber Films by Inkjet-Printing Silver Nanoparticles for Wearables
Albrecht, Andreas; Bobinger, Marco; Salmerón, José F.; Becherer, Markus; Cheng, Gordon; Lugli, Paolo; Rivadeneyra Torres, Almudena
The necessity to place sensors far away from the processing unit in smart clothes or artificial
skins for robots may require conductive wirings on stretchable materials at very low-cost. In this
work, we present an easy method to produce wires using only commercially available materials.
A consumer grade inkjet printer was used to print a wire of silver nanoparticles with a sheet resistance
below 1 W/sq. on a non-pre-strained sheet of elastic silicone. This wire was stretched more than
10,000 times and was still conductive afterwards. The viscoelastic behavior of the substrate results in
a temporarily increased resistance that decreases to almost the original value. After over-stretching,
the wire is conductive within less than a second. We analyze the swelling of the silicone due to the
ink’s solvent and the nanoparticle film on top by microscope and SEM images. Finally, a 60 mm long
stretchable conductor was integrated onto wearables, and showed that it can bear strains of up to
300% and recover to a conductivity that allows the operation of an assembled LED assembled at only
1.8 V. These self-healing wires can serve as wiring and binary strain or pressure sensors in sportswear,
compression underwear, and in robotic applications.
Resonant Hybrid Flyback, a New Topology for High Density Power AdaptorsMedina-Garcia, AlfredoSchlenk, ManfredMorales Santos, Diego PedroRodríguez Santiago, Noelhttps://hdl.handle.net/10481/555402021-12-14T08:35:01ZResonant Hybrid Flyback, a New Topology for High Density Power Adaptors
Medina-Garcia, Alfredo; Schlenk, Manfred; Morales Santos, Diego Pedro; Rodríguez Santiago, Noel
In this article, an innovative power adaptor based on the asymmetrical pulse width
modulation (PWM) flyback topology will be presented. Its benefits compared to other state-of-the-art
topologies, such as the active clamp flyback, are analyzed in detail. It will also describe the control
methods to achieve high efficiency and power density using zero-voltage switching (ZVS) and
zero-current switching (ZCS) techniques over the full range of the input voltage and the output load,
providing comprehensive guidelines for the practical design. Finally, we demonstrate the convenience
of the proposed design methods with a 65 W adaptor prototype achieving a peak efficiency of close
to 95% and a minimum efficiency of 93.4% at full load over the range of the input voltage, as well as
a world-class power density of 22 W/inch3 cased.