Abstract
An electronic nose (E-Nose) is one of the applications for surface acoustic wave (SAW) sensors. In this paper, we present a low-noise complementary metal–oxide–semiconductor (CMOS) readout application-specific integrated circuit (ASIC) based on an SAW sensor array for achieving a miniature E-Nose. The center frequency of the SAW sensors was measured to be approximately 114 MHz. Because of interference between the sensors, we designed a low-noise CMOS frequency readout circuit to enable the SAW sensor to obtain frequency variation. The proposed circuit was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 μm 1P6M CMOS process technology. The total chip size was nearly 1203 × 1203 μm2. The chip was operated at a supply voltage of 1 V for a digital circuit and 1.8 V for an analog circuit. The least measurable difference between frequencies was 4 Hz. The detection limit of the system, when estimated using methanol and ethanol, was 0.1 ppm. Their linearity was in the range of 0.1 to 26,000 ppm. The power consumption levels of the analog and digital circuits were 1.742 mW and 761 μW, respectively.
Highlights
Electronic nose (E-Nose) systems, which are biomimetic olfactory systems for gas sensing [1], have been used in many applications such as food product quality control [2], indoor air quality monitoring, environmental monitoring [3,4], automotive industry production, and clinical diagnosis [5,6]
Implementing a readout circuit with an application-specific integrated circuit (ASIC) reduces the size and power consumption of the system and facilitates moving toward a portable E-Nose system
We used theResults frequency to measure the frequency shift of Surface acoustic wave (SAW) sensors when different
Summary
Electronic nose (E-Nose) systems, which are biomimetic olfactory systems for gas sensing [1], have been used in many applications such as food product quality control [2], indoor air quality monitoring, environmental monitoring [3,4], automotive industry production, and clinical diagnosis [5,6]. The SAW resonator structure was composed of a lithium niobate (LiNbO3) substrate and aurum frequency-type sensors have the advantage of high sensitivity [14]; in the current work,. Studies havesensor reported that coating polymers on sensors factors morethe obvious [15] To this end, a reference was included to generate a frequency that can is leastthe affected by environmental factors.[13,17], and that the resulting sensor array can facilitate improve sensitivity of the sensors. The interface instruments are typically expensive portable; circuit was implemented circuit can convert an analog signaland to not a digital signal, andthe it interface comprises a mixer, low-pass filter, using an ASIC to achieve reduced size, power consumption, and cost. To compress the interference between weSAW designed a low-noise analog multiplexer to switch the signal from each SAW sensor
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