Towards a wearable near infrared spectroscopic probe for monitoring concentrations of multiple chromophores in biological tissue in vivo.
Towards a wearable near infrared spectroscopic probe for monitoring concentrations of multiple chromophores in biological tissue in vivo.
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DOI：
10.1063/1.4954722
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Everdell N
中科院分区：
文献类型：
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作者：
Chitnis D;Airantzis D;Highton D;Williams R;Phan P;Giagka V;Powell S;Cooper RJ;Tachtsidis I;Smith M;Elwell CE;Hebden JC;Everdell N
基于定制的8波长发光二极管（LED）光源，开发了第一种用于功能性近红外光谱的可穿戴多波长技术。设计一种轻型无探针，用于监测生物组织中多种吸收剂（发色团）浓度的变化，其中在近红外波长处最主要的是氧合血红蛋白和脱氧血红蛋白。多个波长的使用使得由较少占主导地位的发色团引起的信号能够更容易地与由血红蛋白引起的信号区分开，从而提供关于组织氧合、血液动力学和代谢的更完整和准确的信息。光谱探头采用四个光电二极管检测器耦合到一个四通道电荷-数字转换器，其中包括一个电荷积分放大器和一个模拟-数字转换器（ADC）。每个检测器使用两个并行的电荷积分器，使得一个电荷积分器积累电荷，而另一个电荷积分器由ADC读出，从而促进连续操作而没有死区时间。检测器系统具有约80 dB的动态范围。定制的光源由8个LED管芯组成，连接到2 mm × 2 mm的基板上，并封装在UV固化环氧树脂中。每20 ms执行一次芯片之间的切换，与检测器积分周期同步，在100 ns内。光谱探头被设计为与同步脑电图测量完全兼容。结果来自对体模的测量和对成年志愿者的功能性大脑激活研究，并且光谱探针的性能被证明与台式宽带光谱系统的性能非常相似。这种光谱探针的多波长能力和便携性将为一系列临床和生命科学应用中的体内研究创造重要机会。
The first wearable multi-wavelength technology for functional near-infrared spectroscopy has been developed, based on a custom-built 8-wavelength light emitting diode (LED) source. A light-weight fibreless probe is designed to monitor changes in the concentrations of multiple absorbers (chromophores) in biological tissue, the most dominant of which at near-infrared wavelengths are oxyhemoglobin and deoxyhemoglobin. The use of multiple wavelengths enables signals due to the less dominant chromophores to be more easily distinguished from those due to hemoglobin and thus provides more complete and accurate information about tissue oxygenation, hemodynamics, and metabolism. The spectroscopic probe employs four photodiode detectors coupled to a four-channel charge-to-digital converter which includes a charge integration amplifier and an analogue-to-digital converter (ADC). Use of two parallel charge integrators per detector enables one to accumulate charge while the other is being read out by the ADC, thus facilitating continuous operation without dead time. The detector system has a dynamic range of about 80 dB. The customized source consists of eight LED dies attached to a 2 mm × 2 mm substrate and encapsulated in UV-cured epoxy resin. Switching between dies is performed every 20 ms, synchronized to the detector integration period to within 100 ns. The spectroscopic probe has been designed to be fully compatible with simultaneous electroencephalography measurements. Results are presented from measurements on a phantom and a functional brain activation study on an adult volunteer, and the performance of the spectroscopic probe is shown to be very similar to that of a benchtop broadband spectroscopy system. The multi-wavelength capabilities and portability of this spectroscopic probe will create significant opportunities for in vivo studies in a range of clinical and life science applications.