LIG-mLPG 传感器：开启多模态健康监测的新‘视’界

研究背景

高血糖威胁全球人类健康，糖尿病患者数量不断上升。传统的血糖检测方法具有侵入性、间歇性，难以实时监测动态血糖水平。可穿戴生物传感器在糖尿病管理领域展现出巨大潜力，能够实现无创、连续的血糖监测。然而，目前的多模态传感器存在冗余传感设计和信号干扰问题，在传感器集成和小型化方面面临挑战。开发高度集成的异构生物传感设备，准确监测生化和物理参数成为迫切需求。

研究成果

柔性可穿戴生物传感器已成为糖尿病管理中追踪人体动态血糖变化的一种有前景的工具。然而，要在进一步推进多模态传感器小型化的过程中，平衡缩小的设备空间和多个冗余传感阵列，仍然是一个挑战。在此，济南大学 Li-Peng Sun、Jie Li、Yi Zhang以及Bai-Ou Guan教授等人提出了一种全新的光电混合多模态光纤传感器，它由对聚二甲基硅氧烷（PDMS）进行激光图案化形成激光诱导石墨烯（LIG）作为叉指电极，以及由封装在PDMS中的光学微纤维制备的长周期光栅（LPG）组成，该长周期光栅由LIG电极的周期性结构调制。这种操作可以紧凑地将两种不同的传感机制，即光学和电学机制，同时集成到单个传感器中。将LIG电极与导电水凝胶相结合，通过在水凝胶中加载葡萄糖氧化酶构建了基于电学机制的柔性葡萄糖生物传感器。同时，微纤维LPG还可作为用于生物力学监测的光谱可用传感器。光学和电学传感器可以同时工作，但彼此独立，特别是在大鼠模型伤口愈合和人类运动场景中。这个平台代表了向能够测量生物力学信息和葡萄糖的多功能传感器迈出的关键一步。相关研究以“Flexible Optoelectronic Hybrid Microfiber Long-period Grating Multimodal Sensor”为题发表在Advanced Science期刊上。

研究亮点

1. 提出一种全新的光电混合多模态光纤传感器 LIG-mLPG，由激光图案化 PDMS 形成的激光诱导石墨烯（LIG）作为叉指电极，以及由 LIG 电极周期结构调制的包埋在 PDMS 中的微光纤长周期光栅（mLPG）组成，将光学和电学两种传感机制集成在一个紧凑的传感器中。

2. 该传感器在压力传感方面，对压力灵敏度高（2.06 nm kPa^-1）、检测限低（0.008 kPa）、响应时间快（~2.8 ms）、恢复时间短（~15.5 ms）且稳定性好；在葡萄糖检测方面，线性范围为 0.02 mM - 13.28 mM，检测限为～0.0246 mM ，具有良好的特异性和稳定性。两种传感机制相互独立，不受彼此干扰。

3. 通过大鼠糖尿病伤口愈合监测实验，验证了传感器对伤口硬度和葡萄糖水平的监测能力；在人体运动实验中，成功实现了对脉搏和汗液葡萄糖信号的同时监测，为糖尿病管理和人体健康评估提供了有力支持。

图文导读

Figure 1. The schematic illustration of LIG-mLPG flexible optoelectronic hybrid multimodal sensor. 

Figure 2. a) Conceptual diagram of mLPG based on laser-induced graphene modulation; b) Top: axial structural diagram of LIG-mLPG; Bottom: crosssectional diagram of LIG-mLPG; c) Top view and d) side view of the simulated amplitude distribution of light propagating through the grating region when the light is launched at resonant (phase-matching, left panel) and non-resonant (non-matching, right panel) wavelengths, respectively; e) Evolution of transmission spectra changes with modulation period number during LIG-mLPG modulation process; f) Relationship between the pitch of grating and resonant wavelength; g) Physical image of LIG-mLPG.

Figure 3. SEM images of a) the top view and b) cross section of the LIG; c) Enlarged SEM image of cross-section of the LIG; d) FTIR of PDMS (red) and LIG (blue); e) Raman spectrum of LIG under different modulation powers; f) \(I_{D} / I_{G}\) (black) and \(I_{2 D} / I_{G}\) (blue) change with laser modulation power; XPS of LIG at g) C 1s; h) O 1s; i) Si 2p.

Figure 4. a) Measured dip wavelength shift of mLPG with a stress step of 2 mN; b) Recorded transmission spectra of a single dip at different pressure levels; c) Repeatability of LIG-mLPG wavelength shift under different pressure levels; d) Measured dip wavelength shift with the applied pressure; e) The response time and recovery time of LIG-mLPG under 1 kPa pressure; f) The stability of LIG-mLPG within a month; Recorded transmission spectra of a single dip under different refractive index g) before and h) after hydrophilic treatment; i) Measured dip wavelength shift with refractive index before and after hydrophilic treatment.

Figure 5. a) I-V characteristics of LIG electrode (positive and negative electrodes connected) within 20 kPa; b) I-V characteristics of GB hydrogel/LIG (interdigital electrode structure) within 20 kPa; c) Comparison of resistance changes between the positive and negative connection pattern of LIG and the GB hydrogel/LIG under different pressures; The storage modulus G and loss modulus \(G^{\prime \prime}\) of GB hydrogel change under different d) shear strains and e) frequencies; f) Rheological recovery test performed with alternately switched shear strain between large strain (50%) and small strain (0.5%); g) The resistance changes of the GB hydrogel doped with GOx under different glucose concentrations (0–25 mM); h) Resistance changes with different glucose concentration; i) Specificity for glucose.

Figure 6. a) The monitoring of wound of the diabetic rat in fiber grating signal (blue) and the change in wound hardness measured by commercial Shore hardness tester (red); b) The monitoring of wound of the diabetic rat in hydrogel electrical signal (blue) and the change in blood glucose measured by commercial blood glucose meters; c) Respiratory signal of the diabetic rat (magnified view of the grating signal in a); d) The monitoring of wound of the healthy rat in fiber grating signal (blue) and the change in wound hardness measured by commercial Shore hardness tester (red); e) The monitoring of wound of the healthy rat in hydrogel electrical signal (blue) and the change in blood glucose measured by commercial blood glucose meters; f) Changes in the wound at the beginning and end of the monitoring.

Figure 7. a) Monitoring on the chest during exercise (no deformation, only sweat); b) Monitoring on the wrist at rest (no sweat, deformation caused by pulse); c) Changes in the pulse wave on the wrist during exercise; d) Changes in glucose concentration in sweat (blue) and blood glucose measurement with a commercial blood glucose meter (red) during exercise; e) Changes in pulse rate over time.

总结与展望

总之，作者展示了一种光电混合多模态可穿戴光纤传感器，它能够同时监测生物力学参数和葡萄糖。这种无缝集成的多模态传感器首先通过在带有多孔激光诱导石墨烯（LIG）的聚二甲基硅氧烷（PDMS）上进行激光图案化，形成叉指电极，该电极还对封装在PDMS中的微纤维的折射率进行调制，从而构建出微纤维长周期光栅（mLPG）。为实现精确的多参数传感，将两组不同的电信号和光信号集成在一个LIG - mLPG传感器中，它们具有不同的运行机制，并且我们对该传感器进行了全面表征，以验证其压力传感可行性以及LIG - mLPG传感器中石墨烯电极的电响应。作为柔性电极并与导电GB水凝胶功能化后，通过在水凝胶中加载葡萄糖氧化酶构建了葡萄糖生物传感器。与现有的多模态传感器相比，LIG - mLPG不仅增强了功能和紧凑性，有效节省了空间，还保持了快速的响应时间、高灵敏度和稳定性。同时，mLPG会在共振波长处触发模式耦合，可同时作为用于生物力学监测的光谱分辨光学传感器。此外，我们深入研究并验证了两种传感机制在不同刺激下的独立性，并进一步展示了该传感器在大鼠模型伤口渗出液葡萄糖检测以及人体模型动脉脉搏和汗液葡萄糖同步监测方面的应用。关于当前传感器的进一步改进，我们可以通过外部刚性电路模块将光学和电信号的两个读出系统集成到一个解调系统中，以便在未来的可穿戴设备中实现更好的柔韧性和舒适性。 

文献链接

https://doi.org/10.1002/advs.202501352 

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