1,720,992 research outputs found
A integrated CMOS circuit for DNA hybridization detection with digital output and temperature control
No full textProducing smart sensing films by means of organic field effect transistors
No full textWe have fabricated the first example of totally flexible field effect device for chemical detection based on an organic field effect transistor (OFET) made by pentacene films grown on flexible plastic structures. The ion sensitivity is achieved by employing a thin Mylar foil as gate dielectric. A sensitivity of the device to the pH of the electrolyte solution has been observed A similar structure can be used also for detecting mechanical deformations on flexible surfaces. Thanks to the flexibility of the substrate and the low cost of the employed technology, these devices open the way for the production of flexible chemical and strain gauge sensors that can be employed in a variety of innovative applications such as wearable electronics, e-textiles, new man-machine interfaces
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Organic Thin-film Transistors for pH Detection
No full textA novel, flexible and ductile organic field-effect transistor (OFET) able to detect pH changes in chemical solutions has been realized and successfully tested. With respect to other organic pH sensors, based on an ISFET-like structure, in our approach the organic transistor is completely separated from the sensing active area and its gate is left floating. The device is biased with a fourth electrode (control-gate) capacitively coupled to the floating-gate. The floating-gate is functionalized by deposition of a layer of thio-amines able to protonize proportionally to the pH value of the solution thus modulating the drain current. The structure does not need an Ag/AgCl counter-electrode since the control-gate is not in contact with the solution. Moreover, the sensing mechanism does not depend on the choice of the dielectric and semiconductor material since the working principle is based on charge separation in the metal induced by the electric field. This structure also simplifies the realization of the fluidics since all the contactable electrodes (drain, source and control-gate) are on the same side of the substrate. A differential measurement approach was adopted in order to get rid of device aging and process-related fluctuations. With the same structure, other chemical species may be detected provided that a proper functionalization procedure is adopted
Flexible organic thin-film transistors for pH monitoring
No full textA novel freestanding flexible device based on an Organic Field Effect Transistor (OFET), able to detect pH changes in chemical solutions thanks to a functionalized loating-gate, was realized and successfully tested. The device is assembled on a lexible film (Mylar), which acts at the same time as gate insulator and as mechanical support for the whole structure. On one side of the foil a control gate and drain/source contacts are photolithographically patterned, and a pentacene active layer deposited; on the opposite side a gold floating gate is defined. The sensor performs the detection of the chemical species placed over the probe area by detecting the associated electric charge: the structure, basically, works as a loating-gate transistor whose threshold voltage is modulated by the surface charge due to the solution under investigation. By properly functionalizing the loating gate surface, sensitivity to different species and the detection of different reactions can be achieved, with the same sensor. In this work we present its application as ion-sensitive device. pH sensitivity is achieved by functionalizing the sensing surface with thio-aminic groups as such groups protonate proportionally to the concentration of H3 O+ ions in the solution. Such a structure does not require a counter-electrode as the OFET is biased through a control gate. Moreover, the working mechanism is independent of the choice of semiconductor, gate or dielectric material, since the OFET is insulated from the solution. The application as DNA sensor is currently under investigation as wel
Active devices based on organic semiconductors for wearable applications
No full textPlastic electronics is an enabling technology for obtaining active (transistor based) electronic circuits on flexible and/or nonplanar surfaces. For these reasons, it appears as a perfect candidate to promote future developments of wearable electronics toward the concept of fabrics and garments made by functional (in this case, active electronic) yarns. In this paper, a panoramic view of recent achievements and future perspectives is given
Organic-based sensor for chemical detection in aqueous solution
No full textWe present a flexible, pentacene-based field-effect device, for the detection of chemical species in aqueous solution. The sensor consists in a double-gate transistor, where the detection is achieved by exploiting the charge sensing capabilities of the floating-gate terminal. To provide the pH -sensitivity, the floating gate is functionalized with thioamine groups as such groups protonize proportionally to the concentration of H3O+ ions in solution. With respect to the existing organic-based devices for pH monitoring, our sensor does not require a counterelectrode and the organic semiconductor is not affected by the contact with the monitored solutio
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