Integrated smart gas flow sensor with 2.6 mW total power consumption and 80 dB dynamic range

• A smart thermal flow sensor for battery-powered applications is proposed.
• Double heater calorimeter and low noise electronic interface are integrated into a single chip.
• The device is fabricated with a custom micromachining post-processing applied to a CMOS process.
• The proposed fabrication method improves sensitivity without affecting the dynamic range.

A thermal flow sensor including sensing structures and a read-out interface in a single chip is proposed. The sensing structure is a microcalorimeter based on a double heater configuration while the low noise electronic interface performs signal reading and offset compensation. The device has been fabricated with a commercial CMOS process followed by a post-processing procedure. Post-processing has been customized in order to increase the thermal insulation of the sensing structures from the silicon substrate and improve the heat exchange between the sensor and the gas flow. Device characterization confirms the effectiveness of the proposed fabrication method in increasing the sensitivity at constant power consumption without affecting the dynamic range.

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