Respiratory diseases, including chronic obstructive pulmonary disease (COPD), are among the leading causes of deaths worldwide. Despite their prevalence, current medical practices lack a method to accurately quantify important parameters within specific lesion areas inside the lung. Our study introduces a catheter probe system designed to fill this critical gap. This novel system integrates a basket forceps with two pressure sensors to simultaneously measure exhalation airflow and static pressure within the pulmonary airway. Utilizing a Pitot tube mechanism, the pressure sensor modules are located outside the body, minimizing the risk of complications during measurement. Proof of concept experiments were performed using an artificial ventilator resembling the real respiration condition inside lung airway. Experimental results demonstrated the feasibility of the proposed concept using catheter probe of up to 550 mm in length, sufficiently allowing its access to human pulmonary airway through mouth. Consistent relation between the dynamic pressure and the mean airflow velocity was obtained independent of the airway size. Local tidal volume measurement was demonstrated at an airway mimicking the 4 th branches of bronchi with 5 mm inner diameter. This innovative approach promises to enhance our understanding and treatment of respiratory diseases by providing detailed insights into lung function previously unattainable through conventional methods.

Thermal sensing mechanism in micro-electro mechanical systems (MEMS) has an inherent potential to realize various flexible physical MEMS sensors due to the absence of resonating structure. In such thermal sensors, it is crucial to limit the thermal mass around the sensing structure to speed-up the time response. The absence of rigid body presents technical challenges to fabricate free-standing sensing elements in flexible MEMS sensors. In such sensors, the thermal mass has been generally limited by the utilization of thin substrates. However, there is a limit when switching to thinner substrate become challenging, mainly due to handling and installation constraints. As a solution, here we propose a laser ablation process to locally remove the unnecessary substrate parts in flexible MEMS thermal sensors. The concept was validated experimentally through thermal analysis and response time measurements under operation as airflow sensors. Time response suppression of up to 50% was confirmed.

Micro-electro mechanical systems (MEMS) accelerometer has been implemented in various applications across industries. To expand its application to textiles, here we propose a facile fabrication and packaging method for fiber-shaped flexible MEMS thermal accelerometer. The sensing structure was fabricated through a standard microfabrication process on a thin polyimide film substrate. The film was then cut into stick shape and packaged inside a flexible resin tube through a facile insertion process. A sensitivity improvement strategy by mitigating the thermal mass around the sensing structure was also introduced. Gravitational acceleration measurement using the proposed sensors was demonstrated using an inclination stage. Finally, measurement of human hand movement using the proposed sensors was demonstrated.

Respiration and heartbeat are among the important vital signs of living beings. Taking advantage of the physical attachment of lung and heart, measurements of both can be performed simultaneously using airflow rate microsensors to measure the respiration airflow. For such airflow rate sensors, the packaging is crucial to define and encapsulate the airflow region. In this study, we propose a facile packaging technique for flexible airflow rate microsensor. The thermal calorimetric sensing structure was fabricated through a standard microfabrication technology on a thin polyimide film. The film was packaged at the center of a resin tube utilizing its buckling. We also proposed an approach to improve the time response by limiting the thermal capacity around the sensing structure through the implementation of a thin substrate for the sensing structure supported by a thicker film. The strategy successfully improved both the time response and sensitivity of the airflow rate sensor. Finally, the utilization of the sensor for simultaneous respiration and heartbeat measurement was demonstrated through an animal experiment using a small animal, namely rat.