Fudan University improves sensor detection accuracy and resolution by 2 orders of magnitude

【Chinese instrument network instrument research and development】 Recently, Dr. Zhu Xiaosong of Fudan University proposed the use of light intensity detection SPR sensing method, the use of monochromatic light incidence and detection of the relationship between the sensor output light intensity and refractive index, in the sensitivity and wavelength detection type With the same conditions as the sensor, the detection accuracy and resolution increased by 2 orders of magnitude. The specific research results were published in the sixth issue of Optics Journal.

Hollow fiber SPR sensor structure diagram (The base pipe material is quartz glass, the metallized film material is silver, and the internal cavity is the flow space of the liquid with high refractive index to be detected)

The experimental device built in the experiment is an experimental system for measuring the SPR transmission spectrum in the dashed box in the upper half. The broad-spectrum light source halogen tungsten lamp and spectrometer are used for wavelength detection SPR sensing experiments. The broad-spectrum light emitted by the tungsten halogen lamp is coupled into the hollow fiber SPR sensor through the multi-mode fiber, and then introduced into the spectrometer (iHR550, Horiba) through the multi-mode fiber jumper to obtain the transmission spectrum. The liquid to be measured is pumped into and pumped out of an air-core optical fiber through two specially-made liquid optical path coupling interface devices under the action of a peristaltic pump. The liquid to be measured is a transparent methyl phenyl silicone oil with different concentrations in the band of 400-800 nm. A mixed solution of kerosene.

Constructed experimental device

In the lower half of the dashed box, an SPR sensing system for intensity detection is used. The light source is a monochromatic semiconductor laser with a wavelength of 532 nm, coupled via a multimode fiber optic patch cord into an air core fiber, using an optical power meter (NOVA II, OPHIR). Measure the output light intensity. By recording and analyzing the relationship between the output light intensity and the refractive index of the liquid filled in the optical fiber, the performance of the hollow fiber SPR sensor in the strength detection mode can be obtained.

The hollow fiber SPR sensor used in the experiment has a maximum resolution of 5.5*10-6 RIU in its linear working area (refractive index detection range of 1.55 to 1.57), compared to the wavelength-detection hollow fiber SPR sensor. Increased by 2 orders of magnitude.

The researchers stated that the use of multiple lasers with different wavelengths at the same time will enable the detection of the sensor to be expanded without replacing the hollow fiber.

(Original title: Researcher improves sensor detection accuracy by 100 times)