Pillalamarri Srikrishnarka
Tampere, Finland
Respiration includes cycles of inhalation and exhalation; is vital for life and by studying the exhaled breath, over 3000 compounds were present. These compounds would suggest the plausible physiological status of that individual. However, measuring the concentration of these species require expensive and exotic instruments such as mass spectrometer which needs expertise high operating costs. Wearable sensors that can target specific components of the breath have been in development in recent times and address the cost, long-time and non-invasive monitoring of health.
Humidity is the major component of the exhaled breath and the rise and fall in the concentration of humidity is synchronous to the respiration rate. The quest for seamless and intelligent respiratory monitoring is having a great relevance. With this aim, a researchers take a leap forward with the integration of lamellar porous film and GaN optopairs. In this exploration, let’s navigate the scientific intricacies that underpin this revolutionary approach. The seminal work accomplished by the scientists from the Southern University of Science and Technology, Schenzhen, China was published in Nano letters.
One of the major limiting factors in sensing humidity from exhaled breath is the slow response and recovery time, as it will fail to record the minute intricacies in breath changes. To short out this problem, researchers developed an optoelectronic device which showed faster response and recovery time. In view of that, a GaN optoelectronic chip was fabricated which acts as both as light source and detector. The device is shown below. . This chip was further integrated on a flexible polyimide film and it exhibited a sensitivity of 13.8 nA/%RH.
(Figure caption: Figure shows the photograph of the packaged microchip for sensing humidity. Copyright © 2023, American Chemical Society)
With this device the authors reported a response and recovery time of 12 and 6 s, which is quicker than the sensors available commercially. Performance of the device compared to commercially available sensor is presented in the figure below. “The compact configuration of a submillimeter size enables the device to be readily integrated with wireless data transfer systems.” the authors reported.
(Figure caption: Performance comparison of the as-fabricated device with a commercial device when measuring changes in humidity in a facemask. The blue, green, and orange shaded areas represent normal breathing, fast breathing, and deep breathing, Respectively. Copyright © 2023, American Chemical Society)