Centre for Nanotechnology, Indian Institute of Technology Guwahati, Assam 781039, India.
Centre for Nanotechnology, Indian Institute of Technology Guwahati, Assam 781039, India; Department of Electronics and Electrical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India.
Biosens Bioelectron. 2017 Aug 15;94:544-551. doi: 10.1016/j.bios.2017.03.049. Epub 2017 Mar 22.
The frequency of breathing and peak flow rate of exhaled air are necessary parameters to detect chronic obstructive pulmonary diseases (COPDs) such as asthma, bronchitis, or pneumonia. We developed a lung function monitoring point-of-care-testing device (LFM-POCT) consisting of mouthpiece, paper-based humidity sensor, micro-heater, and real-time monitoring unit. Fabrication of a mouthpiece of optimal length ensured that the exhaled air was focused on the humidity-sensor. The resistive relative humidity sensor was developed using a filter paper coated with nanoparticles, which could easily follow the frequency and peak flow rate of the human breathing. Adsorption followed by condensation of the water molecules of the humid air on the paper-sensor during the forced exhalation reduced the electrical resistance of the sensor, which was converted to an electrical signal for sensing. A micro-heater composed of a copper-coil embedded in a polymer matrix helped in maintaining an optimal temperature on the sensor surface. Thus, water condensed on the sensor surface only during forcible breathing and the sensor recovered rapidly after the exhalation was complete by rapid desorption of water molecules from the sensor surface. Two types of real-time monitoring units were integrated into the device based on light emitting diodes (LEDs) and smart phones. The LED based unit displayed the diseased, critical, and fit conditions of the lungs by flashing LEDs of different colors. In comparison, for the mobile based monitoring unit, an application was developed employing an open source software, which established a wireless connectivity with the LFM-POCT device to perform the tests.
呼吸频率和呼气峰值流速是检测慢性阻塞性肺疾病（COPD）的必要参数，如哮喘、支气管炎或肺炎。我们开发了一种肺功能即时检测设备（LFM-POCT），包括咬嘴、基于纸张的湿度传感器、微加热器和实时监测单元。制作优化长度的咬嘴可确保呼出的空气集中在湿度传感器上。使用涂有纳米颗粒的滤纸制成的电阻式相对湿度传感器，可轻松跟踪人体呼吸的频率和峰值流速。在强制呼气过程中，湿空气中的水分子在纸张传感器上吸附并凝结，从而降低了传感器的电阻，然后将其转换为电信号进行感测。由嵌入聚合物基质中的铜线圈组成的微加热器有助于保持传感器表面的最佳温度。因此，只有在强制呼吸时水才会在传感器表面凝结，并且在呼气完成后，水分子会从传感器表面快速解吸，传感器会迅速恢复。两种类型的实时监测单元被集成到基于发光二极管（LED）和智能手机的设备中。基于 LED 的单元通过闪烁不同颜色的 LED 来显示肺部的疾病、危急和健康状况。相比之下，对于基于移动的监测单元，开发了一个应用程序，该程序使用开源软件与 LFM-POCT 设备建立无线连接以进行测试。
