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采用近红外光谱法无创测量人体血糖时,葡萄糖浓度变化引起的光强信号微弱,为了实现目标测量精度,需要选择适宜的测量波长使葡萄糖引起的吸收信号水平强于噪声信号水平.本文提出了基于最佳光程长的测量波长选择原则,可在测量灵敏度最大的条件下,评价葡萄糖吸收光谱的测量是否可行.以葡萄糖在水溶液中的测量为例,基于最佳光程长理论,对1 000~2 500 nm的每个波长均进行光程优化,以1 mmol/L的检测浓度为目标,筛选了可行的测量波段.结果表明,即使在最佳光程长下检测,该检测目标对测量光谱的重复性信噪比要求也非常高,当SNR达到10 000∶1时,仅有4个波段满足要求,分别是:1 000~1 160 nm,1 375~1 420 nm,1 590~1 640 nm和1 870~1 910 nm.其中短波长波段1 000~1 160 nm对光谱信噪比的要求最低,且最佳光程长最长,皮肤穿透深度最大,显示了较好的应用前景.这一结果对皮肤中的葡萄糖测量的波长选择有较好的参考价值.此外,本文所提出的波长选择方法也同样适用于采用吸收光谱法对其他物质成分的测量.
When using near infrared spectroscopy to measure human blood glucose non-invasively, the signal of light intensity caused by the change of glucose concentration is faint, so in order to achieve the target measurement accuracy, we need to choose the appropriate measurement wavelength to make the signal of glucose absorption signal stronger than the noise signal. The optimal optical path length of the measurement wavelength selection principle, under the maximum measurement sensitivity, to evaluate the glucose absorption spectrum measurement is feasible.Using glucose measurement in aqueous solution as an example, based on the optimal optical path length theory, 1 000 The optical path optimization was performed at each wavelength of ~ 2 500 nm, and the feasible measurement band was screened at the detection concentration of 1 mmol / L. The results showed that the detection target was good even for the measurement under the optimal optical path length Spectral repeatability of the signal to noise ratio is also very high, when the SNR reaches 10 000: 1, only four bands meet the requirements are: 1 000 ~ 1 160 nm, 1 375 ~ 1 420 nm, 1 590 ~ 1 640 nm and 1870-1 910 nm, of which the short wavelength band 1000-1 160 nm has the lowest spectral signal-to-noise ratio, the best optical path length is the longest, and the skin penetration depth is the largest, which shows a good application Prospects for this result on the skin of the Portuguese Wavelength selection sugar better measurement reference value. Further, the wavelength selection method presented herein are equally applicable to measurements using spectroscopy other absorbent material components.