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Measurement of blood glucose levels (BGLs) is a basic procedure that diabetic patients need to perform several times a day. The conventional standard protocol for on-site measurement, despite several advantages such as portability, low cost, fast response time, and ease of operation, is based on the finger-prick technique to extract blood samples. This process is invasive and cannot provide continuous monitoring, which is the basic condition for optimal control.

Towards the achievement of a noninvasive and continuous BGL monitoring system, various alternative methods have been reported in the literature, involving a lot of researchers, from academic research laboratories to major industrial companies. However, due to the potential impact of the decision made on the basis of the BGL sensor, the requirements in terms of selectivity and sensitivity are so severe that, at the time of this writing, none of the proposed technologies has been able to fulfill them.

Among potential candidates, photoacoustic (PA) techniques have also been investigated, but only the pulse setup, since the continuous-wave (CW) requires a constant and reproducible local environment (i.e., cavity size) for operation, a condition impossible to realize in vivo. The CW-PA methods have then been limited to mainly gas-trace detection. However, we recently developed two CW-PA-based protocols that don't exhibit this cavity-size dependency, which opens the door to a new field of research. After a brief description of the two methods and their specific characteristics, this presentation will then discuss the in vitro (with pure aqueous solution of glucose) and in vivo first experimental results. The challenges ahead before applying these methods to BGL monitoring are still huge and require further study, both in vitro and in vivo. However, despite primarily developed for noninvasive and continuous BGL monitoring, the techniques exhibit interesting properties that may also lead to potential application in many other fields.

Author’s Short Biography

Serge Camou is currently a Research Scientist in the Microsensor Research Group, NTT Microsystem Integration Laboratories, NTT Corporation. He received the B.S., M.S. and Ph.D degrees in physics from Cergy-Pontoise (1994), Paris 7 (1996), and Franche-Comte (2000) Universities in France, respectively.

After two years as a JSPS (Japan Society for the Promotion of Science) fellow at the University of Tokyo doing research on DNA lab-on-chip devices, he moved to NTT Microsystem Integration Laboratories in 2003 and became involved in the development of portable sensors based on several technologies for various applications: the detection of benzene compounds in air and liquid samples based on the UV absorption spectroscopy, the detection of foodborne pathogens based on surface plasmon resonance (SPR), and point-of-care testing based on the photoacoustic techniques. His main research interests are then centered on applications dealing with environmental and biomedical analyses involving several techniques that best fit the requirements. He is a member of the IEEE Photonics Society.