| 1. |
- Andersson, Henrik, et al.
(author)
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Processing and Characterization of a MOS Type Tetra Lateral Position Sensitive Detector with Indium Tin Oxide Gate Contact
- 2008
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In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 8:9-10, s. 1704-1709
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Journal article (peer-reviewed)abstract
- A 2-D tetra lateral position sensitive detector (PSD) based on the metal-oxide-semiconductor (MOS) principle has been manufactured and characterized. The active area of the device is 5 nun x 5 mm and the intention is to use the central 4 nun x 4 nun for low nonlinearity measurements. The gate contact is made of indium tin oxide (ITO) that is a degenerate electrically conducting semiconductor, which, in addition, is also transparent in the visible part of the spectrum. The use of a MOS structure results in a processing with no necessity to use implantation or diffusion in order to make the resistive p-layer as in a conventional p-n junction lateral effect PSD. Position measurements show good linearity in the middle 4 nun x 4 mm area. Within the middle 2.1 mm x 2.1 mm, the nonlinearity is within 1.7% of the active area with a position detection error of maximum 60 mu m. Measured MOS IV characteristics are compared to a level 3 spice model fit and show good agreement. The threshold voltage is determined to be -0.03 V. Responsivity measurements show a high sensitivity in the visible spectral region.
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| 2. |
- Jason, Johan, et al.
(author)
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Experimental Study of an Intensity Modulated Fiber-Optic Position Sensor with a Novel Readout System
- 2008
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In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 8:7, s. 1105-1113
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Journal article (peer-reviewed)abstract
- An intensity modulated fiber-optic position sensor, based on a fiber to bundle coupling and a readout system using a CMOS image camera together with fast routines for position extraction and calibration, is experimentally demonstrated. Further a simulation of the complete sensor system setup is made, and possible sources of error are analyzed experimentally. Our analysis indicates the theoretical limit of the system and identifies the causes of system errors. The results are encouraging for further development of the system setup.
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| 3. |
- Mattsson, Claes, 1978-, et al.
(author)
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Design of a Micromachined Thermopile Infrared Sensor with a Self-Supported SiO2/SU-8 Membrane
- 2008
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In: IEEE Sensors Journal. - Piscataway, USA : IEEE. - 1530-437X .- 1558-1748. ; 8:12, s. 2044-2052
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Journal article (peer-reviewed)abstract
- In the infrared region of the spectrum thermoelectric detectors such as the thermopile, are extensively used. These detectors rely on the well-known Seebeck effect, in which there is a direct conversion of thermoelectric differentials into electrical voltage. The temperature difference over thermocouple junctions is in general, created by forming a thin membrane connected to the silicon bulk. In many existing thermopiles, materials such as Si and Si3N4 have been used as membrane. These materials suffer from relatively high thermal conductivity, which lowers the membrane temperature and reduces the sensitivity of the detector. A material such as SU-8 2002 has a much lower thermal conductivity and is applied using standard photolithographic processing steps. This work presents thermal simulations regarding the use of SU-8 2002 as a thermal insulating membrane as compared to Si and Si3N4. The simulation results presented show that the temperature increase in a 5 µm SiO2/SU-8 membrane is about 9% higher than in a 1 µm Si3N4 membrane, despite the membrane thickness being increased by a factor of 5. A thermopile consisting of 196 serially interconnected Ti/Ni thermocouples positioned on a 5 µm SiO2/SU-8 2002 membrane has been fabricated. The sensitivity of the fabricated device has been evaluated in the infrared region, using a 1.56 µm IR laser and a xenon arc lamp together with a monochromator. The measurement results show a sensitivity of approximately 5 V/W over the wavelength range between 900 - 2200 nm. Measurements performed in a vacuum chamber show that the sensitivity of the detector could be increased by more than a factor of 3 by mounting the detector in a vacuum sealed capsule.
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| 4. |
- Mattsson, Claes, 1978-, et al.
(author)
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Experimental evaluation of a thermopile detector with SU-8 membrane, in a carbon dioxide meter setup
- 2009
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In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 9:12, s. 1633-1638
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Journal article (peer-reviewed)abstract
- Continuous control of the carbon dioxide levels in the ventilation systems in office buildings and public schools has been shown to increase productivity and save money. However, these measurement systems require further developments in order to be more cost effective. This paper presents an evaluation of an Al/Bi thermopile detector with a 4 µm thin SiO2/SU-8 membrane in a CO2 meter application using the NDIR (Non-Dispersive Infrared Technology). The system consists of an 11 cm aluminum tube, used as the sample chamber and in which a light source and a thermopile detector with a 4.26 µm optical bandpass filter are positioned on its opposite sides. The light source is pulsed with a frequency of 0.5 Hz. The voltage response of the Al/Bi thermopile is measured for different CO2 concentrations, and, as expected according to the Lambert-Beer law, there is an exponential decrease in the measured intensity. The absolute response is about 50 % lower than for a commercial HMS J21 thermopile from Heimann Sensor GmbH. In relative terms, on the other hand, the Al/Bi thermopile is more sensitive for changes in the CO2 concentration. At 7500 ppm, the voltage response has decreased to 40 % of the reference response measured in the nitrogen atmosphere.
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| 5. |
- Unander, Tomas, et al.
(author)
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Characterization of Printed Moisture Sensors in Packaging Surveillance Applications
- 2009
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In: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 9:8, s. 922-928
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Journal article (peer-reviewed)abstract
- This work presents a study on the performance of printed low cost moisture sensors fabricated using conductive ink on paper substrates. The sensors are intended to add value to the surveillance of packages. Two different kinds of sensors are evaluated and characterized. The two sensors have similar geometrical shapes, but different measuring principles are employed. The first sensor is measuring the moisture content in cellulose based substrates, while the second is measuring high levels of relative humidity in the surroundings. The sensors have been developed so that they can be integrated into Radio Frequency Identification (RFID) systems for surveillance in logistic chains. A laboratory setup of a RFID tag with sensor capability based on an ordinary passive RFID tag has been shown.
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