Surface plasmon resonant (SPR) phenomenon is widely researched for various purposes, among which biomedical sensing is getting more attentions as they are suitable for surface functionalization acting as a bio recognition element to detect different biological infections. The common method of surface resonant is propagating SPR such as reflection method. Another method which is widely used for SPR is localized SPR which use nanostructures in thin metal. Various structures such as slit only, slit- groove and slit-multiple groove are used for generation of SPR and obtaining the optimum optical transmittance through the structure. The number and position of slits and grooves affect transmittance through the structure. In this paper we propose a new structure of cross slit-grooves structure, which includes slit-groove structure in grid form. The slit-grooves structures are arranged in such a way that it forms symmetrical structure in two dimension with slit and groove and hence the transmittance with cross slit-grooves structure increases significantly. The cross slit-grooves structure takes the advantage of symmetrical slit and groove by using both dimensional structures for generating SPR which increases the transmittance through the structure. A comparison of proposed slit-grooves grid structure with straight slit-grooves structure is carried out to show the increase in transmittance through the cross slit-grooves grid structure. Plane wavelength of 400 nm to 900 nm is used for the analysis of transmittance through the Ag slit-grooves grid structures with glass substrate. We also measure the change in transmittance with change in refractive index, which can be helpful for measuring different chemical analytes, and hence can be used for different chemical and biosensors applications.
We analyze the transmission property of nanostructures made on silver and gold metal for the applications in optical biosensors. Various structures such as slit only, slit groove slit, and multiple slit and groove structures are taken into account to find the effect of various physical parameters such as number of grooves, number of slits and others on the transmission of different wavelength light sources through the structure. A broad wavelength of 400 nm to 900 nm is used to analyze the transmission through the structure. With these structures and broad light source, change in transmission intensity is analyzed with the change in the refractive index. The change in refractive index of the analyte varies transmission intensity and wavelength shift at the output beam which can be used for sensing the amount of analyte such as monitoring glucose amount on blood/saliva, hydrogen peroxide and others. The detection of these analytes can be used to detect the different disease. The analysis of the transmittance through the nanostructure can be used for the detection of several disease such as diabetes and others through the saliva, blood and others non-invasively.
It represents a viable solution for the realization of a portable biosensor platform that could screen/diagnose acute
myocardial infarction by measuring cardiac marker concentrations such as cardiac troponin I (cTnI), creatine kinase MB
(CK-MB), and myoglobin (MYO) for application to u-health monitoring system. The portable biosensor platform
introduced in this presentation has a more compact structure and a much higher measuring resolution than a conventional
spectrometer system. Portable guided-mode resonance (GMR) biosensor platform was composed of a biosensor chip
stage, an optical pick-up module, and a data display panel. Disposable plastic GMR biosensor chips with nano-grating
patterns were fabricated by injection–molding. Whole blood filtration and label-free immunoassay were performed on
these single chips, automatically. Optical pick-up module was fabricated by using the miniaturized bulk optics and the
interconnecting optical fibers and a tunable VCSEL (vertical cavity surface emitting laser). The reflectance spectrum
from the GMR biosensor was measured by the optical pick-up module. Cardiac markers in human serum with
concentrations less than 0.1ng/mL were analyzed using a GMR biosensor. Analysis time was 30min, which is short
enough to meet clinical requirements. Our results show that the GMR biosensor will be very useful in developing lowcost
portable biosensors that can screen for cardiac diseases.
A fiber-optic voltage sensor is demonstrated with a new signal processing scheme that displays the magnitude and the waveform of applied signal using fringe counting method. The detrimental polarization modulation effect of the sensor was overcome by using a fiber-optic half-wave plate.