Piezoresistive Membrane Surface Stress Sensors for Characterization of Breath Samples of Head and Neck Cancer Patients

Abstract

For many diseases, where a particular organ is affected, chemical by-products can be found in the patient’s exhaled breath. Breath analysis is often done using gas chromatography and mass spectrometry, but interpretation of results is difficult and time-consuming. We performed characterization of patients’ exhaled breath samples by an electronic nose technique based on an array of nanomechanical membrane sensors. Each membrane is coated with a different thin polymer layer. By pumping the exhaled breath into a measurement chamber, volatile organic compounds present in patients’ breath diffuse into the polymer layers and deform the membranes by changes in surface stress. The bending of the membranes is measured piezoresistively and the signals are converted into voltages. The sensor deflection pattern allows one to characterize the condition of the patient. In a clinical pilot study, we investigated breath samples from head and neck cancer patients and healthy control persons. Evaluation using principal component analysis (PCA) allowed a clear distinction between the two groups. As head and neck cancer can be completely removed by surgery, the breath of cured patients was investigated after surgery again and the results were similar to those of the healthy control group, indicating that surgery was successful.

Statistical Evaluation of Total Expiratory Breath Samples Collected throughout a Year: Reproducibility and Applicability toward Olfactory Sensor-Based Breath Diagnostics

“…Recent studies have demonstrated the potential ability of MSS as an olfactory system in some different analysis, in settings such as quantification of alcohol contents from vapours of various types of liquids [ 18 ], quantification of a ternary mixture consisting of water, ethanol, and methanol [ 19 ], discrimination between spices and herbs [ 20 ] even with free-hand measurements [ 21 ], and detection of small amounts of VOCs contained in body odour [ 22 ]. To our interest, a pilot study analysing exhaled breath using MSS showed the possibility that patients with head and neck cancer can be discriminated from healthy volunteers [ 23 ] and patients before surgery from those after surgery as well as healthy control persons [ 24 ]. Although these previous studies have demonstrated promising sensitivity and specificity of MSS, it is known that the conditions of samples (e.g., temperature, humidity, and interfering gases) affect the signals measured by artificial olfactory systems based on chemical sensor arrays, including MSS.…”

A Literature Review of the Potential Diagnostic Biomarkers of Head and Neck Neoplasms

“…Next to spectrometric analysis, VOCs can be detected by sensor technology [electronic noses (eNoses)] that recognizes the bulk of VOCs as a breath print, but without identifying individual VOCs. Using eNoses, HNSCC patients could be differentiated from controls with sensitivities and specificities ranging between 77–90% and 80–90%, respectively, underlining the difference in breath print and their use as diagnostic tool ( 40 , 41 , 43 ). Also, eNoses have shown to be promising for differential diagnosis, in which the breathprint of HNSCC patients was different from those with lung cancer, colon cancer and bladder cancer with, respectively, 85, 79, and 80% sensitivity and 84, 81, and 86% specificity ( 45 , 49 , 54 ).…”

Exhaled breath analysis in the diagnosis of head and neck cancer

“…In HNC, Hakim et al suggested that breath analysis using an artificial nose could be utilized as a test to follow‐up after treatment of HNC especially for those cases at high‐risk of developing second primary tumors. Moreover, breath analysis from cured patients who underwent resection of HNC was similar to breath analysis of healthy control, which potentially indicates a successful surgery . Interestingly, Hartwig et al collected breath samples before and after surgical treatment of oral squamous cell carcinoma and compared the breath analysis for each case.…”