Low-cost embedded spirometer based on micro machined polycrystalline thin film

There is a great need for a low cost and low power consumption portable spirometer for the home care of respiratory diseases. A mobile monitoring system utilizing Bluetooth and mobile messaging services (SMS) with low-cost hardware equipment is proposed. A proof of concept prototype has been developed and implemented to enable transmission of a flow or volume of gas during inspiratory and expiratory process signal of a patient, which can be expanded to include other vital signs. Communication between a mobile smart-phone and the spirometer is implemented using the popular personal area network standard specification Bluetooth. We used SMS for transmission, the mobile phone plots the received signal and displays the flow measurement application software running on the client mobile phone itself, where the plot can be captured and saved as an image before transmission. The acquired signal is transmitted via the Bluetooth to the processing and diagnostic unit with wireless protocol between sensors and the electronics board. The flow measurement is done with a silicon hot wire anemometer manufactured with MEMS technology. The design, manufacturing, calibration, and basic characterization of MEMS hot-wire anemometer and digital spiromerter is presented.

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► We design a very low power consumption and wearable micro spirometer.
► The micro-machined thermal flow sensor fits the specific requirements in the patient respiration control of high dynamic flow range combined with a fast response time.
► The sensor exhibits a high accuracy, a short response time (<0.5 ms) and a low power consumption.