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Now showing items 17 - 19 of 19

  • CMOS X-ray Image Sensor Array

    J.G. Rocha   G. Minas   S. Lanceros-Mendez   J. Silva  

    This paper describes a pixel array for x-rays imaging consisting in an 8x8 photodiode array fabricated in CMOS technology; with the respective readout circuit. Above the photodiodes; an array of scintillating CsI:Tl crystals are placed. So; the x-ray energy is first converted to visible light by the scintillating crystals; which is then detected by the photodiodes. The photocurrent produced by each photodiode is amplified; converted to a voltage and stored in a capacitor. Finally; the voltage of each capacitor is read by the readout circuit.
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  • Piezoelectric β-PVDF polymer films as fluid acoustic microagitator

    G. Minas   S. Lanceros-Mendez   J. Serrado Nunes   J. G. Rocha   V. F. Cardoso  

    The main objective of this paper is to describe a fluidic acoustic microagitation system based on a Poly(Vinylidene Fluoride) polymer. This system benefits from the high piezoelectric properties presented by the beta-phase of the polymer (β;-PVDF) converting an electrical signal into acoustics vibrations. These vibrations can be used in microfluid systems to enhance fluids mixture and reaction. Experimental results regarding the influence of the area and thickness of the piezoelectric β;-PVDF polymer on the velocity of reaction of some biological fluids are presented. Moreover, the incorporation of the β;-PVDF underneath microfluidic structures of a lab-on-a-chip with an automatic electronic control is referred.
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  • X-Ray CMOS detector array with scintillating light guides

    S. Lanceros-Mendez   A. J. Ferreira   P. Goncalves   G. Minas   L. Goncalves   R. A. Dias   A. V. Fernandes   J. G. Rocha  

    This paper presents a preliminary study concerning an x-ray detector design to analyze a small area with high spatial resolution. The indirect method of x-ray detection is used. In this design, an array of scintillating CsI:Tl crystals, encapsulated in aluminum, is coupled with an array of photodetectors. This structure, patented and described by the authors in detail in previous works, can be obtained using the SU-8 negative photoresist as a sacrificial layer. The experimental work consisted in the deposition of a scintillator layer, and an aluminum layer, on the active area of a commercially available digital imaging sensor, thus supporting the developed detector design. X-ray imaging tests were performed using the PHILIPS X’;Pert equipment. Promising results were obtained, featuring high resolution and detail.
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