Figure 3 - uploaded by Anuj Baskota
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A) Calibration curve of moisture: QIMAGE plotted against soil VWC%. B) Calibration curve of unwrapped phase shift varying with temperature for 5 random pixels. C) Phase and the interpolated temperature changing over time measured by the GHz imager and BME 280.

A) Calibration curve of moisture: QIMAGE plotted against soil VWC%. B) Calibration curve of unwrapped phase shift varying with temperature for 5 random pixels. C) Phase and the interpolated temperature changing over time measured by the GHz imager and BME 280.

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Conference Paper
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This work reports a single chip GHz ultrasonic micro-imager for imaging soil temperature, morphology, moisture, and pests such as nematodes. A 128×128 pixel array of 50×50 µm piezoelectric Aluminum Nitride (AlN) transducers is integrated onto 130nm CMOS substrates. The imager-surface is segmented into three sensing regions: soil temperature, moistu...

Contexts in source publication

Context 1
... plotted to form images of the soil. To remove any DC offsets, no-echo signals ( [I_N] and [Q_N]) were also obtained. These are the signals that were read after the echo died out. For moisture calibration, the wet and dry pixel's average return signal [QIMAGE] was measured to correlate with the soil VWC%. The obtained calibration plot is shown in Fig. 3A. Temperature can be measured through the phase change of the return echoes, as the speed of sound in silicon changes with temperature [7]. Therefore, the phase was calculated using the following ...
Context 2
... The derived phase plotted for 5 pixels is shown in Fig. 3B. An experiment was also performed to compare the imager's temperature reading with a standard temperature sensor (BME 280). Here, the BME 280 was placed next to our imager's surface and an infrared lamp located around 20 cm away (Fig. 2C) from the surface was turned on for 50 seconds. Fig. 3C shows the phase shift and the interpolated ...
Context 3
... The derived phase plotted for 5 pixels is shown in Fig. 3B. An experiment was also performed to compare the imager's temperature reading with a standard temperature sensor (BME 280). Here, the BME 280 was placed next to our imager's surface and an infrared lamp located around 20 cm away (Fig. 2C) from the surface was turned on for 50 seconds. Fig. 3C shows the phase shift and the interpolated temperature values with changing frames for two random pixels (sampled at 6.5 fps) along with BME 280 temperature sensor data. The ultrasonically measured temperature follows the BME 280 sensor data, validating the ultrasonic temperature ...

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Citations

... Soil information, including soil temperature, moisture, and soil compaction, is one of the main components of agricultural information [13][14][15][16][17]. Soil information can be obtained by the ultrasonic method. Baskota et al. [18] studied a single-chip GHz ultrasonic micro-imager for imaging soil temperature, morphology, moisture, and pests. Zhang et al. [19] measured the freezing state of soil by the ultrasonic method. ...
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Ultrasonic detection is one of the main methods for information detection and has advantages in soil detection. Ultrasonic signals attenuate in soil, resulting in unique propagation laws. This paper studies the propagation laws of ultrasound in soil, focusing on the propagation characteristics of ultrasonic continuous signals at the transducer–soil interface. This study uses excitation frequency and amplitude as experimental factors and employs the discrete element simulation method to analyze the vibration characteristics of soil particles. It reveals the relationship between changes in soil pressure at the interface and the movement of the transducer. The results show that the motion curve of the transmitting transducer lags behind the soil pressure changes, and the energy of the ultrasonic signal increases with higher excitation frequency and amplitude. Specifically, the peak value of the first wave |H0| at 40 kHz and 60 kHz is 210% and 263% of that at 20 kHz, respectively. When the excitation amplitude increases from 0.005 mm to 0.015 mm, the value of the peak value of other waves |H| increases by 323%. This paper preliminarily reveals the propagation laws of ultrasonic continuous signals at the transducer–soil interface, providing theoretical support for the development of ultrasonic soil property detection instruments.
... In this paper we use a simple drop-drying technique to demonstrate the potential of GHz imager for nematode identification. In previous works, we have demonstrated GHz imaging of nematodes in air, water, and soil [10,11]. In this work, we show differentiating two morphologically similar nematode species using the ultrasonic reflectometry data. ...
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