Limits...
A Meliorated Multi-Frequency Band Pyroelectric Sensor.

Hsiao CC, Liu SY, Siao AS - Sensors (Basel) (2015)

Bottom Line: The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes.The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor.The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Design Engineering, National Formosa University, No. 64, Wunhua Rd., Huwei Township, Yunlin County 632, Taiwan. cchsiao@nfu.edu.tw.

ABSTRACT
This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

No MeSH data available.


Schematic diagram of the meliorated multi-frequency band pyroelectric sensor (unit: μm).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4541877&req=5

sensors-15-16248-f001: Schematic diagram of the meliorated multi-frequency band pyroelectric sensor (unit: μm).

Mentions: A general pyroelectric sensor is composed of a single pyroelectric layer sandwiched between top and bottom electrodes and built on a substrate with an insulating layer. As the thicknesses of the pyroelectric layers determine the thermal time constant (τT) under pyroelectric materials and electrode areas already fixed, the thermal time constant determines the optimal working frequency of the pyroelectric sensors. The meliorated multi-frequency band pyroelectric sensor, consisting of four ZnO pyroelectric layers with various thicknesses, and top and bottom electrodes, was built on a silicon substrate with a thermal-insulation (silicon nitride) layer to reduce heat and electric loss. Figure 1 shows the schematic diagram of the meliorated multi-frequency band pyroelectric sensor. The thinnest ZnO pyroelectric layer was deposited by sputtering with high qualities, and the others were deposited by AD. The sputtered ZnO layer acted as a producer of the responsivity at higher frequency bands, while the aerosol ZnO layers detected the electrical signals of the sensors at lower frequency bands. In the AD, the starting powder was commercially available ZnO (Top Nano Technology Co. Ltd., New Taipei, Taiwan). The properties of the starting ZnO powder are shown in Table 1. Table 2 shows the process parameters used for the AD method. The powder was subjected to heat treatment at 150 °C for 1 h using an oven to reduce moisture content and agglomerated particles in the powder before ZnO films were deposited. ZnO powder with high moisture content became severely agglomerated particles for absorbing the kinetic energy when the powder impacted against the substrate. Subsequently, furnace annealing was used on the ZnO films to improve film quality. A furnace annealing system (SJ High Technology Company, Taiwan), consisting of a single zone tube furnace with tube furnace Model T21-303, a single zone programmable temperature control console with controller Model SJ-C01, a cooling system, and a vacuum system, were used for the ZnO film annealing in an N2 ambient. The process parameters of furnace annealing for the ZnO films are shown in Table 3. The film thickness was further probed by a surface analyzer (ET-4000AK, Kosaka, Tokyo, Japan). The XRD patterns and the SEM micrographs of the ZnO layers could refer previous studies [7,14].


A Meliorated Multi-Frequency Band Pyroelectric Sensor.

Hsiao CC, Liu SY, Siao AS - Sensors (Basel) (2015)

Schematic diagram of the meliorated multi-frequency band pyroelectric sensor (unit: μm).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541877&req=5

sensors-15-16248-f001: Schematic diagram of the meliorated multi-frequency band pyroelectric sensor (unit: μm).
Mentions: A general pyroelectric sensor is composed of a single pyroelectric layer sandwiched between top and bottom electrodes and built on a substrate with an insulating layer. As the thicknesses of the pyroelectric layers determine the thermal time constant (τT) under pyroelectric materials and electrode areas already fixed, the thermal time constant determines the optimal working frequency of the pyroelectric sensors. The meliorated multi-frequency band pyroelectric sensor, consisting of four ZnO pyroelectric layers with various thicknesses, and top and bottom electrodes, was built on a silicon substrate with a thermal-insulation (silicon nitride) layer to reduce heat and electric loss. Figure 1 shows the schematic diagram of the meliorated multi-frequency band pyroelectric sensor. The thinnest ZnO pyroelectric layer was deposited by sputtering with high qualities, and the others were deposited by AD. The sputtered ZnO layer acted as a producer of the responsivity at higher frequency bands, while the aerosol ZnO layers detected the electrical signals of the sensors at lower frequency bands. In the AD, the starting powder was commercially available ZnO (Top Nano Technology Co. Ltd., New Taipei, Taiwan). The properties of the starting ZnO powder are shown in Table 1. Table 2 shows the process parameters used for the AD method. The powder was subjected to heat treatment at 150 °C for 1 h using an oven to reduce moisture content and agglomerated particles in the powder before ZnO films were deposited. ZnO powder with high moisture content became severely agglomerated particles for absorbing the kinetic energy when the powder impacted against the substrate. Subsequently, furnace annealing was used on the ZnO films to improve film quality. A furnace annealing system (SJ High Technology Company, Taiwan), consisting of a single zone tube furnace with tube furnace Model T21-303, a single zone programmable temperature control console with controller Model SJ-C01, a cooling system, and a vacuum system, were used for the ZnO film annealing in an N2 ambient. The process parameters of furnace annealing for the ZnO films are shown in Table 3. The film thickness was further probed by a surface analyzer (ET-4000AK, Kosaka, Tokyo, Japan). The XRD patterns and the SEM micrographs of the ZnO layers could refer previous studies [7,14].

Bottom Line: The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes.The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor.The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Design Engineering, National Formosa University, No. 64, Wunhua Rd., Huwei Township, Yunlin County 632, Taiwan. cchsiao@nfu.edu.tw.

ABSTRACT
This article proposes a meliorated multi-frequency band pyroelectric sensor for detecting subjects with various velocities, namely extending the sensing frequency under good performance from electrical signals. A tactic, gradually increasing thickness of the ZnO layers, is used for redeeming drawbacks of a thicker pyroelectric layer with a tardy response at a high-frequency band and a thinner pyroelectric layer with low voltage responsivity at a low-frequency band. The proposed sensor is built on a silicon substrate with a thermal isolation layer of a silicon nitride film, consisting of four pyroelectric layers with various thicknesses deposited by a sputtering or aerosol deposition (AD) method and top and bottom electrodes. The thinnest ZnO layer is deposited by sputtering, with a low thermal capacity and a rapid response shoulders a high-frequency sensing task, while the thicker ZnO layers are deposited by AD with a large thermal capacity and a tardy response shoulders a low-frequency sensing task. The fabricated device is effective in the range of 1 KHz~10 KHz with a rapid response and high voltage responsivity, while the ZnO layers with thicknesses of about 0.8 μm, 6 μm, 10 μm and 16 μm are used for fabricating the meliorated multi-frequency band pyroelectric sensor. The proposed sensor is successfully designed, analyzed, and fabricated in the present study, and can indeed extend the sensing range of the multi-frequency band.

No MeSH data available.