Figure 6 - uploaded by Anuj Baskota
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1.85 GHz ultrasonic images from nematodes in wet soil experiment: (A) Water is completely covering the sensor. (B) As the water dries up, nematodes can still be observed in the dried regions.
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Plant parasitic nematodes are soil-borne microscopic worms that parasitize plant roots, reducing cropy ields for economically important crops such as soybeans, sugarbeets, and strawberries, to name a few. This paper presents the concept of using a GHz ultrasonic imaging array to image nematodes, as a way to quantify nematode populations within soil...
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Context 1
... last experiment involved seeing if the sensor can detect nematodes in soil. The sensor board is placed in soil, with the entire sensor surface immersed in soil. Water containing nematodes was added to the soil. As shown in Fig. 6A, as the water seeps through the soil, the nematodes within it move into contact with the sensors. As opposed to the nematodes in water experiment, the nematodes can be very easily distinguished in the ultrasonic image. This is likely because the small gaps within the soil that the water flows through brings the nematodes directly in ...
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Citations
... This is a first priority of our future studies, and is therefore beyond the scope of the presented work. Future refinements of the method should include several aspects: (1) Non-straight sections of the flow field can be monitored using longitudinal waves exploring acoustic impedance mismatching at the BPP-water interface [53]. (2) Exploring the lower sensitivity limits for droplet volumes smaller than 50 nL, which will be needed for PEMFC operation at higher flow rates or dry conditions [43]. ...
To date, the efficiencies of proton exchange membrane exchange fuel cells (PEMFCs) are limited by the water flooding issue. Water monitoring systems, which are a crucial step to overcoming these flooding-related problems, are mostly either invasive or compromise on the temporal resolution and field of view. Thus, we propose an ultrasonic-Lamb-waves-based, real-time, nondestructive water monitoring system. Briefly, ultrasonic transducers are mounted on the back side of bipolar plates (BPPs) exciting Lamb waves along flow channels incorporated in BPPs. Echo signals from water droplets in the channels are also received by the transducers. Thus, with the knowledge of Lamb wave propagation velocity, water droplets are spatially resolved by time-of-flight of each droplet echo. Meanwhile, the energy of each droplet induced echo wave packet is used to quantify the local flooding status. We have implemented a flexible and generic system adaptable to various flow field designs. The working principle was demonstrated for
ex-situ
conditions with a BPP with a 25 cm2
active area. A water sensitivity of at least 50 nL was realized, allowing for studying droplet and slug flows in PEMFCs. A 1.3 mm spatial resolution and a 2 kHz temporal resolution were simultaneously achieved. The high-performance water monitoring opens new horizons to study dynamic water evolution in channels of PEMFCs using cost-effective instrumentation, which may pave the way towards more efficient high-power PEMFCs with increased lifetimes.
... The overall packaging of the GHz ultrasonic imager is compact and handheld, with a silicon surface as the sensing region ( Figure 1A). More details on the circuitry and fabrication of the GHz imager, with another application of imaging nematodes, are described in our previous works [3,4]. Ultrasonic pulses generated by the transmitting pixels are transmitted and reflected off the backside of the silicon. ...
... Here we demonstrate the use of 2D 128x128 AlN CMOS integrated T/R pixels to verify lens operation. The GHz Micro-Imager enables measurement of the return magnitude and phase to characterize the lens phase shifting operation [4]. This demonstration establishes a methodology to characterize and optimize complex siliconbased 2D ultrasonic impedances at high GHz frequencies. ...
... The total size of the ultrasonic imager is 6.4x6.4mm. Different 0.9mm diameter lens designs were tested with the imager [4], [18]. ...
... The ultrasonic imager, implemented at Geegah Inc, is a compact device fabricated with 130nm CMOS technology [4], [18]. The imager has 128x128 arrays of 50μm wide AlN transmit/receive transducers. ...
... While other MEMS technologies such as electrostatic MEMS are capable of being integrated into CMOS, Piezo-MEMS stands out in the sheer variety of devices enabled by thin film AlN/AlScN. The CMOS compatibility of AlN has enabled numerous MEMS devices to be integrated onto CMOS, including FBAR resonators [1], piezoelectric micromachined ultrasonic transducers (PMUT) [2], piezoelectric transformers [3], contour-mode resonators (CMR) [4], microphones [5], and GHz ultrasonic transducers [6][7]. Other devices enabled by thin film AlN or AlScN include piezoelectric gyroscopes [8], optical waveguides and modulators [9], RF switches [10], and ferroelectric memories [11], among many others. ...
... With several thousand pixels, the grouping enabled the ability to analyze the return signal differently, allowing specific information to be extracted from each of these groups (Fig. 1C). The GHz imager used in this work uses the same device layer stack as reported by Kuo et al [6]. ...
... This falls in the range of the average size for S.carpocapsae [9]. Previous experiments have used optical microscopes to confirm that these shapes correspond to the presence of nematodes [6]. Throughout the multi-day experiments, images of soil can also be seen changing with water addition and soil drying. ...
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, moisture, and direct soil imaging of morphology and pest, such as nematodes. The imager's compact size and potentially low price can significantly reduce the barrier to the success of digital agriculture, which requires data collections over millions of acres in a cost-effective way with high sampling resolution.