Noncontact speckle-based optical sensor for detection of glucose concentration using magneto-optic effect

Abstract

We experimentally verify a speckle-based technique for noncontact measurement of glucose concentration in the bloodstream. The final device is intended to be a single wristwatch-style device containing a laser, a camera, and an alternating current (ac) electromagnet generated by a solenoid. The experiments presented are performed in vitro as proof of the concept. When a glucose substance is inserted into a solenoid generating an ac magnetic field, it exhibits Faraday rotation, which affects the temporal changes of the secondary speckle pattern distributions. The temporal frequency resulting from the ac magnetic field was found to have a lock-in amplification role, which increased the observability of the relatively small magneto-optic effect. Experimental results to support the proposed concept are presented.

Remote photonic sensing of cerebral hemodynamic changes via temporal spatial analysis of acoustic vibrations

“…As shown in Ref. [27], the presented method can sense nanometric vibrations. Hence, by using this method the hemodynamic changes can be sensed.…”

“…[27], the presented method can sense nanometric vibrations. The method is based on sensing of acoustic vibrations that are generated by the brain blood vessels.…”

“…This effect is more direct than the later hemodynamic response; however, it is a much smaller effect. Nano-vibrations due to blood flow changes and tissue oxygenation affect light waves and cause the self-interference random patterns (ie, speckle patterns) to change in time and in space [25][26][27][28]. The method senses sound waves of brain blood vessels using analysis of spatial temporal back-scattered light.…”

“…The described configuration includes observation of the secondary speckle patterns [23,24] that are created by illuminating the skull using a laser beam. Nano-vibrations due to blood flow changes and tissue oxygenation affect light waves and cause the self-interference random patterns (ie, speckle patterns) to change in time and in space [25][26][27][28]. By using this approach, the temporal nanometric vibrations of the speckle patterns due to hemodynamic responses can be tracked [29][30][31][32][33][34].…”

Demonstration of a Speckle Based Sensing with Pulse-Doppler Radar for Vibration Detection

“…Other applications which utilize an optical approach for the extraction and separation of remote vibration sources were used for biomedical measurements, such as monitoring heart rate, breathing, blood pressure, blood oximetry, blood coagulation [ 1 , 2 , 3 , 4 ], bone fractures [ 5 ], melanoma [ 6 ], and glucose concentration in blood [ 7 , 8 ].…”