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Highly sensitive sensors are one of the enabling technologies for the biomarker detection in early stage diagnosis of pathologies. We have developed a self-sensing nanomechanical force probe able for detecting the unbinding of single couples of biomolecular partners in nearly physiological conditions. The embedding of a piezoresistive transducer into a nanomechanical cantilever enabled high force measurement capability with sub 10-pN resolution. Here, we present the design, microfabrication, optimization, and complete characterization of the sensor. The exceptional electromechanical performance obtained allowed us to detect biorecognition specific events underlying the biotin-avidin complex formation, by integrating the sensor in a commercial atomic force microscope. ; This work has been supported by the Spanish Ministry of Science and Innovation through projects NANOSELECT-CSD2007-00041(Consolider-Ingenio 2010) and TEC2011-23600, by the European Union through the COST ACTION TD1002 and partly supported by the PRIN-MIUR Project No. 2009 WPZM4S and by AIRC (Grant IG10412.) ; Peer reviewed

Under the terms of the Creative Commons Attribution (CC BY) license to their work. ; The effect of geometrical asymmetries on the piezoresistive transduction in suspended double clamped beam nanomechanical resonators is investigated. Tapered silicon nano-beams, fabricated using a fast and flexible prototyping method, are employed to determine how the asymmetry affects the transduced piezoresistive signal for different mechanical resonant modes. This effect is attributed to the modulation of the strain in pre-strained double clamped beams, and it is confirmed by means of finite element simulations. ; The research leading to these results received funding from the European Union's Seventh Framework Programme FP7/2007-2013, under Grant Agreement No. 318804 (SNM). Support is also acknowledged from project Force for future (CSD2010-00024). ; Peer Reviewed

A top-down clamped-clamped beam integrated in a CMOS technology with a cross section of 500 nm × 280 nm has been electrostatic actuated and sensed using two different transduction methods: capacitive and piezoresistive. The resonator made from a single polysilicon layer has a fundamental in-plane resonance at 27 MHz. Piezoresistive transduction avoids the effect of the parasitic capacitance assessing the capability to use it and enhance the CMOS-NEMS resonators towards more efficient oscillator. The displacement derived from the capacitive transduction allows to compute the gauge factor for the polysilicon material available in the CMOS technology. © 2015 by the authors; licensee MDPI, Basel, Switzerland. ; This work has been supported by the Spanish MINECO and European Union FEDER programme under project TEC2012–32677 (NEMS-in-CMOS). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer Reviewed

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0). ; We present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID) and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers ; This work was supported by the Spanish Ministry of Economy and Competitiveness through projects No. TEC2011-23600, Nanoselect-CSD2007-00041 (Consolider-Ingenio 2010 programme) and MAT2011- 27553-C02, including FEDER funds, by the Aragón Regional Government, and by the EU Sudoe Interreg TRAIN2 proyect. ; Peer Reviewed

The present work reports on the development of piezoresistive TixCuy thin films, deposited on polymeric substrates (PET). The general idea was to analyse the influence of the Cu concentration on the signal response of the Ti-based transducers, exploring the possibility to use this thin film system as force and deformation sensors in biomedical sensing devices. The GLancing Angle Deposition, GLAD, technique was used to change the typical normal columnar growth microstructure into inclined (zigzag-like) architectures, aiming to tune the mechanical and electrical responses of the thin films, which may offer unique opportunities for several sensing devices. Inclined (zigzag grown) thin films were prepared with increasing amounts of Cu and characterized in terms of the most relevant properties for sensing applications. The piezoresistive response was analyzed trough the evaluation of the Gauge Factor, K. The incident angles of the particle flux  = 45º were used to prepare the nano-architectured zigzag TixCuy thin films. The Gauge factor ranges from 1.24 ± 0.03 to 16.34±0.43 for intermetallic Ti0.92Cu0.08 and pure Cu thin films, respectively. For the deposited thin films small voids are formed and the voids density decreases considerably with increasing Cu content. Taking in account the: electrical resistance linearity, low noise and the highest K value found for TixCuy films (K= 3.6±0.1), the most promising results were obtained when the polymer was coated with a stoichiometry ofTi0.37Cu0.63. The overall set of results also show the viability of these materials to be used as piezoresistive sensors, namely in biological environments, such as catheters, needles or endoscopes with sensing capabilities. ; The authors also thank FCT for financial support: A. Ferreira and C. Lopes thanks the FCT for grant SFRH/BPD/102402/2014 and SFRH/BD/103373/2014. The authors thank financial support from the Basque Government Industry Department under the ELKARTEK Program. SLM thanks the Diputación de Bizkaia for financial support ...

Tactile sensors are basically arrays of force sensors that are intended to emulate the skin in applications such as assistive robotics. Local electronics are usually implemented to reduce errors and interference caused by long wires. Realizations based on standard microcontrollers, Programmable Systems on Chip (PSoCs) and Field Programmable Gate Arrays (FPGAs) have been proposed by the authors for the case of piezoresistive tactile sensors. The solution employing FPGAs is especially relevant since their performance is closer to that of Application Specific Integrated Circuits (ASICs) than that of the other devices. This paper presents an implementation of such an idea for a specific sensor. For the purpose of comparison, the circuitry based on the other devices is also made for the same sensor. This paper discusses the implementation issues, provides details regarding the design of the hardware based on the three devices and compares them. ; This work has been partially funded by the Spanish Government under contracts TEC2006-12376 and TEC2009-14446.

Printed sensors find an increasing interest essentially due to their characteristics of flexibility and low cost per unit area. In this work a screen printed Wheatstone bridge is presented, suitable for strain sensing applications. A piezoresistive ink composite based on biocompatible thermoplastic elastomer styrene-ethylene/butylene-styrene (SEBS) as matrix and multi-walled carbon nanotubes (MWCNT) as nanofillers was used as a piezoresistive sensing material. Different deposition techniques, such as, screen printing, spray painting and drop casting were evaluated in order to optimize the resistance variation related to the piezoresistive effect. Several Wheatstone bridges with one and two sensors were designed to obtain an output sensitivity as a function of the strain submitted to the sensors. Further, different sensor geometries were evaluated to maximize the strain output sensitivity. Electro-mechanical bending tests showed a good linearity and a sensitivity up to 18 mV/V in the all screen printed half Wheatstone bridge output with two MWCNT/SEBS sensors. ; This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014. V. Correia and P. Costa thank the FCT for the SFRH/BPD/97739/2013 and SFRH/BPD/110914/2015 grants respectively. The authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R. SLM thank financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs. ...

A generation of piezoresistive sensors (force or deformation) fully processed by printing technologies is increasingly being implemented in applications due to advantages as a large-area application, simple device, integration, and high flexibility. This work reports the development of a fully printed piezoresistive (5 × 5 sensor) matrix in which an organic thin-film transistor (OTFT) is placed in each sensor to allow the readout of each sensor independently and thus reducing the crosstalk between individual sensors. The manufacturing was carried out using inkjet printing for the deposition of materials in a thin layer stacked on top of each other to obtain functional OTFTs. The piezoresistive nanocomposite sensors, based on multiwalled carbon nanotubes within an elastomeric styrene-ethylene-butadiene-styrene (SEBS) polymer matrix, were fabricated by screen printing. The fabrication and characterization of both OTFT and sensors are presented and discussed in detail. The inkjet-printed OTFTs (width/length channel ratio of ∼130) show a drain-source current (IDS) of 150 μA with a gate-source voltage of −40 V. Gauge factors of up to 5.9 were obtained for the sensors, resulting in a current variation of 1.5 μA. This corresponds to about 0.7% of the total IDS in a deformation cycle ; FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019, UID/FIS/04650/2019 and projects PTDC/FIS-MAC/28157/2017 and PTDC/BTM-MAT/28237/2017, SFRH/BPD/110914/2015 (PC). V.C. thanks FCT for the junior researcher contract (DL57/2016). We acknowledge funding from the European Union's Horizon 2020 Programme for Research, ICT-02-2018 - Flexible and Wearable Electronics. Grant agreement no. 824339 – WEARPLEX. Financial support from the Basque Government Industry and Education Department under the ELKARTEK, HAZITEK and PIBA ...

Wearable electronic sensor was prepared on a light and flexible substrate. The breathing sensor has a broad assumption and great potential for portable devices in wearable technology. In the present work, the application of a flexible thermoplastic polyurethane/multiwalled carbon nanotubes (TPU/MWCNTs) strain sensor was demonstrated. This composite was prepared by a novel technique using a thermoplastic filtering membrane based on electrospinning technology. Aqueous dispersion of MWCNTs was filtered through membrane, dried and then welded directly on a T-shirt and encapsulated by a thin silicone layer. The sensing layer was also equipped by electrodes. A polymer composite sensor is capable of detecting a deformation by changing its electrical resistance. A T-shirt was capable of analyzing a type, frequency and intensity of human breathing. The sensitivity to the applied strain of the sensor was improved by the oxidation of MWCNTs by potassium permanganate (KMnO4) and also by subsequent application of the prestrain. ; Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; Operational Program Research and Development for Innovations; TBU in Zlin [IGA/CPS/2018/005, IGA/CPS/2019/010]; national budget of the Czech Republic, within project CPS-strengthening research capacity [CZ.1.05/2.1.00/19.0409]; European Regional Development Fund (ERDF)European Union (EU)