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The aim of this study was to develop a circuit for an inexpensive portable biosensing system based on surface plasmon resonance spectroscopy. This portable biosensing system designed for field use is characterized by a special structure which consists of a microfluidic cell incorporating a right angle prism functionalized with a biomolecular identification membrane, a laser line generator and a data acquisition circuit board. The data structure, data memory capacity and a line charge-coupled device (CCD) array with a driving circuit for collecting the photoelectric signals are intensively focused on and the high performance analog-to-digital (A/D) converter is comprehensively evaluated. The interface circuit and the photoelectric signal amplifier circuit are first studied to obtain the weak signals from the line CCD array in this experiment. Quantitative measurements for validating the sensitivity of the biosensing system were implemented using ethanol solutions of various concentrations indicated by volume fractions of 5%, 8%, 15%, 20%, 25%, and 30%, respectively, without a biomembrane immobilized on the surface of the SPR sensor. The experiments demonstrated that it is possible to detect a change in the refractive index of an ethanol solution with a sensitivity of 4.99838 × 105 ΔRU/RI in terms of the changes in delta response unit with refractive index using this SPR biosensing system, whereby the theoretical limit of detection of 3.3537 × 10−5 refractive index unit (RIU) and a high linearity at the correlation coefficient of 0.98065. The results obtained from a series of tests confirmed the practicality of this cost-effective portable SPR biosensing system.

Geometric calibration can eliminate systematic errors in the imaging parameters to improve the positioning accuracy. The conventional method depends on high-accuracy control data to detect and eliminate systematic errors; therefore, it requires a satellite to scan the calibration fields before carrying out geometric calibration, which reduces its timeliness. This paper presents an interior self-calibration method to eliminate CCD distortions without using high-accuracy control data on the calibration fields, in contrast to the conventional calibration method. Instead, only the 90-m digital elevation data from the global shuttle radar topography mission (90m-SRTM) are used. Extraordinarily, the calibration accuracy of this method is not restricted by the inadequate accuracy of 90m-SRTM, and very promising accuracy comparable to that of the conventional calibration method is achieved. In the experiment, multispectral images obtained by the ZY02C satellite were used, and the results show that the proposed method can eliminate the high-order distortion without the use of high-accuracy control data but only with the 90m-SRTM. Moreover, the internal accuracies of the calibrated images are better than 0.8 pixels. Compared to the conventional method using high-accuracy control data for calibration, the difference between the two methods is only about 0.02 pixels, which verifies the effectiveness of this method. [ABSTRACT FROM AUTHOR]