High-sensitivity humidity sensors with ZnO nanorods based two-port surface acoustic wave delay line

Surface acoustic wave (SAW) sensors are a class of piezoelectric MEMS sensors which can achieve high sensitivity and excellent robustness. A surface acoustic wave ethanol sensor using ZnO nanorods has been developed and tested. Vertically oriented ZnO nanorods were produced on a ZnO/128∘ rotated Y-cut LiNbO3 layered SAW device using a solution growth method with zinc nitrate, hexamethylenetriamine, and polyethyleneimine. The nanorods have average diameter of 45 nm and height of 1 μm. The SAW device has a wavelength of 60 um and a center frequency of 66 MHz at room temperature. In testing at an operating temperature of 270 with an ethanol concentration of 2300 ppm, the sensor exhibited a 24 KHz frequency shift. This represents a significant improvement in comparison to an otherwise identical sensor using a ZnO thin film without nanorods, which had a frequency shift of 9 KHz.

Download Full-text

Flexible Surface Acoustic Wave Based Temperature and Humidity Sensors

MRS Proceedings ◽

10.1557/opl.2014.111 ◽

2014 ◽

Vol 1659 ◽

pp. 75-80 ◽

Cited By ~ 4

Author(s):

X.L. He ◽

J. Zhou ◽

W.B. Wang ◽

W.P. Xuan ◽

D.J. Li ◽

...

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Lamb Waves ◽

High Sensitivity ◽

Zno Films ◽

Humidity Sensors ◽

Saw Devices ◽

Flexible Surface ◽

Temperature And Humidity ◽

Temperature Coefficient Of Frequency

ABSTRACTFlexible surface acoustic wave (SAW) based temperature and humidity sensors were fabricated and characterized. ZnO piezoelectric films were deposited on polyimide substrates by DC magnetron sputtering. ZnO films possess (0002) crystal orientation with large grain sizes of 50∼70 nm. SAW devices showed two wave modes, namely the Rayleigh and Lamb modes, with the frequencies at fR ∼132MHz and fL∼427MHz respectively for a wavelength of 12 μm device. The two resonant frequencies have a temperature coefficient of frequency (TCF) of −423ppm/K and −258ppm/K for the Rayleigh and Lamb waves, respectively. The SAW sensors exhibited a good repeatability in responding to cyclic change of humidity. The responses of the sensors increase with the increase in humidity, and the sensitivity increases with the decrease in wavelength. A high sensitivity of 34.7 kHz/10%RH has been obtained from a SAW device without any surface treatment, demonstrated that the flexible SAW humidity sensors are very promising for application in flexible sensors and microsystems.

Download Full-text

Viscosity sensor using a surface acoustic wave delay line

The Journal of the Acoustical Society of America ◽

10.1121/1.2026093 ◽

1988 ◽

Vol 84 (S1) ◽

pp. S199-S199 ◽

Cited By ~ 2

Author(s):

Tooru Nomura ◽

Syu Iino ◽

Tsutomu Yasuda

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Delay Line ◽

Viscosity Sensor

Download Full-text

A high sensitivity wireless mass-loading surface acoustic wave DNA biosensor

Modern Physics Letters B ◽

10.1142/s0217984914500560 ◽

2014 ◽

Vol 28 (07) ◽

pp. 1450056 ◽

Cited By ~ 9

Author(s):

Hua-Lin Cai ◽

Yi Yang ◽

Yi-Han Zhang ◽

Chang-Jian Zhou ◽

Cang-Ran Guo ◽

...

Keyword(s):

Acoustic Wave ◽

Surface Acoustic Wave ◽

Dna Sequences ◽

Biological Treatment ◽

High Performance ◽

Processing System ◽

High Sensitivity ◽

Treatment Method ◽

Saw Sensor ◽

Target Dna

In this paper, a surface acoustic wave (SAW) biosensor with gold delay area on LiNbO 3 substrate detecting DNA sequences is proposed. By well-designed device parameters of the SAW sensor, it achieves a high performance for highly sensitive detection of target DNA. In addition, an effective biological treatment method for DNA immobilization and abundant experimental verification of the sensing effect have made it a reliable device in DNA detection. The loading mass of the probe and target DNA sequences is obtained from the frequency shifts, which are big enough in this work due to an effective biological treatment. The experimental results show that the biosensor has a high sensitivity of 1.2 pg/ml/Hz and high selectivity characteristic is also verified by the few responses of other substances. In combination with wireless transceiver, we develop a wireless receiving and processing system that can directly display the detection results.

Download Full-text