17 marzo 2012

Accesso al web per nonvedenti: soluzione innovativa con nanotecnologie. Un articolo pubblicato su "Advanced Functional Materials".

nanoBraille Uno schermo tattile per consentire l'accesso al web ai nonvedenti? Un gruppo di ricerca internazionale (Università di Tokyo e di Hiroshima University, Max Planck Institute for Solid State Research, AIST, RIKEN) ha costruito un foglio Braille basato su transistor a matrice organica a film sottile (TFT) e nano-attuatori al carbonio in grado di fornire le informazioni tattili al nonvedente. I ricercatori, già autori di uno studio su schermi Braille nel 2010 (IEEE Transactions on Electron Devices: Large-Area Flexible Ultrasonic Imaging System With an Organic Transistor Active Matrix), ha pubblicato i risultati più recenti su "Advanced Functional Materials": "A 4 V Operation, Flexible Braille Display Using Organic Transistors, Carbon Nanotube Actuators, and Organic Static Random-Access Memory". Tra i vantaggi di questa innovazione: il basso voltaggio (4 V contro 40V del precedente sistema)
Andrea Mameli www.linguaggiomacchina.it 17 marzo 2012

A 4 V Operation, Flexible Braille Display Using Organic Transistors, Carbon Nanotube Actuators, and Organic Static Random-Access Memory
Kenjiro Fukuda et al. Advanced Functional Materials. Volume 21, Issue 21, pages 4019–4027, November 8, 2011.
Abstract
A sheet-type Braille display operating at 4 V has been successfully fabricated by integrating organic an static random-access memory (SRAM) array with carbon nanotube (CNT)-based actuators that are driven by organic thin-film transistors (control-TFTs). The on current of organic control-TFTs that drive CNT actuators exceeds 3 mA, the mobility exceeds 1 cm2 V−1s−1, and the on/off ratio exceeds 105 at an operational voltage of 3 V. By adjusting the process time for the formation of the aluminum oxide dielectrics, the threshold voltage of the organic TFTs can be systematically controlled. This technique leads to an improved static noise margin of the SRAM and enables its stable operation with a short programming time of 2 ms at a programming voltage of 2 V. As a demonstration of the operation of one actuator with one control-TFT and SRAM: the displacement of actuator exceeds 300 μm at an operation voltage of 4 V, which is large enough for a blind person to recognize the pop-up of braille dots. Integrating the SRAM array reduces the frame rate of a 12 dot × 12 dot display from 1/21.6 s to 1/2.9 s.
white Braille dot
Photograph of the actuator with a white Braille dot in the two static states (up and down). (Reprinted with permission from Wiley-VCH Verlag)

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