Optofluidic Formaldehyde Sensing: Towards On-Chip Integration

International audienceFormaldehyde (HCHO), a chemical compound used in the fabrication process of a broad range of household products, is present indoors as an airborne pollutant due to its high volatility caused by its low boiling point ( T=−19 °C). Miniaturization of analytical systems towards palm-held devices has the potential to provide more efficient and more sensitive tools for real-time monitoring of this hazardous air pollutant. This work presents the initial steps and results of the prototyping process towards on-chip integration of HCHO sensing, based on the Hantzsch reaction coupled to the fluorescence optical sensing methodology. This challenge was divided into two individually addressed problems: (1) efficient airborne HCHO trapping into a microfluidic context and (2) 3,5–diacetyl-1,4-dihydrolutidine (DDL) molecular sensing in low interrogation volumes. Part (2) was addressed in this paper by proposing, fabricating, and testing a fluorescence detection system based on an ultra-low light Complementary metal-oxide-semiconductor (CMOS) image sensor. Two three-layer fluidic cell configurations (quartz–SU-8–quartz and silicon–SU-8–quartz) were tested, with both possessing a 3.5 µL interrogation volume. Finally, the CMOS-based fluorescence system proved the capability to detect an initial 10 µg/L formaldehyde concentration fully derivatized into DDL for both the quartz and silicon fluidic cells, but with a higher signal-to-noise ratio (SNR) for the silicon fluidic cell ( SNRsilicon=6.1 ) when compared to the quartz fluidic cell ( SNRquartz=4.9 ). The signal intensity enhancement in the silicon fluidic cell was mainly due to the silicon absorption coefficient at the excitation wavelength, a(λabs=420 nm)=5×104 cm−1 , which is approximately five times higher than the absorption coefficient at the fluorescence emission wavelength, a(λem=515 nm)=9.25×103 cm−

Miniaturization of fluorescence sensing in optofluidic devices

International audienceSuccessful development of a micro-total-analysis system (μTAS, lab-on-a-chip) is strictly related to the degree of miniaturization, integration, autonomy, sensitivity, selectivity, and repeatability of its detector. Fluorescence sensing is an optical detection method used for a large variety of biological and chemical assays, and its full integration within lab-on-a-chip devices remains a challenge. Important achievements were reported during the last few years, including improvements of previously reported methodologies, as well as new integration strategies. However, a universal paradigm remains elusive. This review considers achievements in the field of fluorescence sensing miniaturization, starting from off-chip approaches, representing miniaturized versions of their lab counter-parts, continuing gradually with strategies that aim to fully integrate fluorescence detection on-chip, and reporting the results around integration strategies based on optical-fiber-based designs,optical layer integrated designs, CMOS-based fluorescence sensing, and organic electronics. Further successful development in this field would enable the implementation of sensing networks in specific environments that, when coupled to Internet of-Things (IoT) and artificial intelligence (AI), could provide real-time data collection and, therefore, revolutionize fields like health, environmental, and industrial sensing

The Canadian celiac health survey – the Ottawa chapter pilot

BACKGROUND: Celiac disease may manifest with a variety of symptoms which can result in delays in diagnosis. Celiac disease is associated with a number of other medical conditions. The last national survey of members of the Canadian Celiac Association (CCA) was in 1989. Our objective was to determine the feasibility of surveying over 5,000 members of the CCA, in addition to obtaining more health related information about celiac disease. METHODS: The Professional Advisory Board of the CCA in collaboration with the University of Ottawa developed a comprehensive questionnaire on celiac disease. The questionnaire was pre-tested and then a pilot survey was conducted on members of the Ottawa Chapter of the CCA using a Modified Dillmans' Total Design method for mail surveys. RESULTS: We had a 76% response to the first mailout of the questionnaire. The mean age of participants was 55.5 years and the mean age at diagnosis was 45 years. The majority of respondents presented with abdominal pain, diarrhea, fatigue or weight loss. Prior to diagnosis, 30% of respondents consulted four or more family doctors. Thirty seven percent of individuals were told they had either osteoporosis or osteopenia. Regarding the impact of the gluten-free diet (GFD), 45% of individuals reported that they found following a GFD was very or moderately difficult. The quality of life of individuals with celiac disease was comparable to the mean quality of life of Canadians. CONCLUSION: On the basis of our results, we concluded that a nationwide survey is feasible and this is in progress. Important concerns included delays in the diagnosis of celiac disease and the awareness of associated medical conditions. Other issues include awareness of celiac disease by health professionals and the impact of the GFD on quality of life. These issues will be addressed further in the national survey

Fungal Origins of the Bicyclo[2.2.2]diazaoctane Ring System of Prenylated Indole Alkaloids

Over eight different families of natural products, consisting of nearly seventy secondary metabolites, which contain the bicyclo[2.2.2]diazaoctane ring system, have been isolated from various Aspergillus, Penicillium, and Malbranchea species. Since 1968, these secondary metabolites have been the focus of numerous biogenetic, synthetic, taxonomic, and biological studies, and, as such, have made a lasting impact across multiple scientific disciplines. This review covers the isolation, biosynthesis, and biological activity of these unique secondary metabolites containing the bridging bicyclo[2.2.2]diazaoctane ring system. Furthermore, the diverse fungal origin of these natural products is closely examined and, in many cases, updated to reflect the currently accepted fungal taxonomy