Multi-band millimeter wave / terahertz breath sensor based on molecular absorption spectroscopy

呼吸分析在临床诊断中具有巨大的潜力。它具有固有的安全性和非侵入性。它可以用来检测疾病，监测疾病进展或监测治疗。尽管呼吸分析有很大的潜力，但它仍然没有得到广泛的应用。其中一个原因是仪器不足，这往往是昂贵的，难以使用，而且不便携。此外，大多数实用的传感器只能检测一种物种，而且仅用一种仪器不可能同时测量许多挥发性有机化合物（VOCs）的特征模式。Humboldt-Universität zu Berlin， Leibniz-Institut fr Innovative Mikroelektronik和Universität Marburg的研究小组的共同目标是开发一种新的，非常敏感和高度特异性的人体呼吸分析传感器。传感器的检测原理是毫米波（mmW）和太赫兹（THz）频率的分子吸收光谱。该传感器可同时检测人体呼吸中的多种相关挥发性有机化合物。它由一个频率可调的毫米波/太赫兹发射机（TX）和一个接收器（RX）组成。在之前的一个项目中，这种毫米波呼吸传感器的可行性已经在240 GHz左右的频率上得到了证明，并且呼吸气体已经被测量出来。在该项目中，传感器的灵敏度、特异性和选择性将得到显著提高。这将通过增加输出功率，灵敏度和线性的TX和RX来实现。传感器的频率覆盖范围将扩大到以480 GHz和720 GHz为中心的两个频段，从而可以以更高的灵敏度检测到更多的气体。此外，还将探索一种利用TX谐波的新型多波段光谱方法。新的吸收和气体处理系统将减少系统损耗并提高灵敏度。由于缺乏毫米波/太赫兹频率下挥发性有机化合物的光谱数据，因此将使用专用的实验室光谱仪对许多挥发性有机化合物进行光谱研究。这项新技术将被集成到便携式毫米波/太赫兹呼吸传感器中。该传感器将在Universität马尔堡通过将毫米波/太赫兹呼吸传感器应用于肺部疾病患者进行评估。最后，将评估毫米波/太赫兹呼吸传感器在诊所和救护车上实际应用的可行性。这种跨学科的合作将大大有助于在常规医学诊断中实施呼吸分析。

Breath analysis has an enormous potential in clinical diagnosis. It is inherently safe and non-invasive. It can be used to detect diseases, monitor disease progression or monitor therapy. Despite of its potential breath analysis is still not widely used. One of the reasons is inadequate instrumentation, which is often expensive, difficult to use, and not portable. In addition most practical sensors can only detect one species and it is not possible to measure a characteristic pattern of many volatile organic compounds (VOCs) simultaneously with only one instrument. The common objective of the groups at Humboldt-Universität zu Berlin, Leibniz-Institut für Innovative Mikroelektronik, and Universität Marburg is to develop a novel, very sensitive and highly specific sensor for human breath analysis. The detection principle of the sensor is molecular absorption spectroscopy at millimeter wave (mmW) and terahertz (THz) frequencies. The sensor will allow detecting many relevant VOCs in human breath simultaneously. It consists of a frequency tunable mmW/THz transmitter (TX) and a receiver (RX). In a prior project the feasibility of such a mmW breath sensor has been demonstrated at frequencies around 240 GHz and breath gases have been measured. In this project the sensitivity, specificity and selectivity of the sensor will be significantly improved. This will be achieved by increasing the output power, sensitivity and linearity of the TX and RX. The frequency coverage of the sensor will be extended by two frequency bands centered at 480 GHz and 720 GHz, which allows more gases to be detected with higher sensitivity. Also a novel multi-band spectroscopy approach using the harmonics of the TX will be explored. A new absorption and gas handling system will reduce system losses and increase sensitivity. Since there is a lack of spectroscopic data of VOCs at mmW/THz frequencies a number of VOCs will be spectroscopically investigated using a dedicated laboratory spectrometer. The new developments will be integrated into a portable mmW/THz breath sensor. This sensor will be evaluated at Universität Marburg by applying the mmW/THz breath sensor to patients with lung diseases. Finally, the feasibility of a mmW/THz breath sensor for practical use in clinics and ambulances will be assessed. This interdisciplinary collaboration will contribute significantly to the implementation of breath analysis for routine medical diagnostics.