生物电信号是人体神经系统控制组织和器官活动与功能的一种重要电生理信号。人体在进行各种生理活动时体内可兴奋细胞会产生电位变化，并在人体内产生不断变化的电场。因此，可以从人体的各种组织和器官中获取相应的电生理信号。电生理信号可以反映器官和组织的生理状态，在健康监测和疾病诊断等方面发挥着不可替代的作用，同时，电生理信号可以作为信息媒介，在人机交互和康复训练等领域发挥重要作用。电极是收集电生理信号的必要组成部分，但电极与生物组织之间固有的机械差异给高质量电生理信号的采集带来了巨大挑战。设计与生物组织模量匹配的生物电极可以有效解决这一问题。

聚二甲基硅氧烷（PDMS）具有优异的生物相容性、化学稳定性和机械柔性，是制备电生理电极的理想材料。目前基于PDMS的柔性电极仍然面临两个重大问题：1. 电极-生物界面机械性质不匹配，缺乏长期稳定性，难以获得高质量的电生理信号。2. 制备条件苛刻繁琐，大面积和图案化困难，难以制备阵列电极。基于此，本论文从生物-电子界面出发，围绕非离子表面活性剂调控PDMS力学性能，设计制备了PDMS基的粘性生物电极并用于电生理信号检测，为PDMS基柔性电极的简便制备及高质量电生理信号采集提供了有效策略。主要研究内容包括以下几个部分：

一、粘性PDMS生物基底的性质调控。首先，探究不同HLB值的非离子表面活性剂对PDMS力学性质、光学性质的影响。其中，基于Tween85改性的PDMS（T-a-PDMS）生物基底最大剥离力可达0.995 N。在550 nm处，其透光率为84%。之后探究了固化温度、基底厚度对T-a-PDMS生物基底力学性能的影响，由于非离子表面活性剂极性对温度的依赖性，T-a-PDMS生物基底的最佳固化温度范围为40℃-50℃。通过力学模型计算得出T-a-PDMS生物基底与皮肤共形接触的临界厚度为250 μm，当厚度小于250 μm时，基底可与皮肤共形贴附。通过多次水洗、反复剥离测试及长达两个月的室温储存，T-a-PDMS生物基底依然具有出色的粘附性能。

二、粘性LIG/PDMS生物电极的制备与表征。基于T-a-PDMS生物基底，结合导电材料激光诱导石墨烯（LIG），制备了粘性LIG/PDMS生物电极。SEM、Raman光谱、XPS等表征手段证明PI成功被激光诱导转化为高质量、多孔结构的三维石墨烯。探究表明LIG具有优异的导电性，面电阻可在18.6 Ω/□到6.6 Ω/□范围内调节。同时，T-a-PDMS生物基底稳定的粘附使该电极具有较低的皮肤界面阻抗。细胞实验表明该电极材料没有细胞毒性，对人表皮细胞几乎没有影响，可用于人体表皮电生理信号记录。

三、粘性LIG/PDMS生物电极的应用。将该生物电极作为电生理信号测量电极并以普通PDMS基底制备的LIG/PDMS电极作为对照，从信噪比和基线噪音等方面评估信号质量。由于具有稳定的电极-皮肤界面，该电极可获得高质量的电生理信号。除此之外，该电极在微弱电生理信号及多位点电生理信号检测时表现出强大的信号记录能力。

Bioelectrical signal is an important electrophysiological signal which controls the activity and function of tissues and organs in human nervous system. When the human body carries out various physiological activities, the excitable cells in the body will produce potential changes, and produce constantly changing electric fields in the human body. Therefore, the corresponding electrophy-siological signals can be obtained from various tissues and organs of the human body. Electrophysiological signals can reflect the physiological state of organs and tissues, and play an irreplaceable role in health monitoring and disease diagnosis. In addition, electrophysiological signals can be used as information media, it plays an important role in human-computer interaction and rehabilitation training. Electrode is an essential part of collecting electrophysiological signals, but the inherent mechanical differences between electrode and biological tissue bring great challenges to collecting high-quality electrophysiological signals. This problem can be effectively solved by designing a bio-electrode which can match the modulus of biological tissue.

Polydimethylsiloxane (PDMS) is an ideal material for preparing electrophysiological electrode because of its excellent biocompatibility, chemical stability and mechanical flexibility. At present, flexible electrodes based on PDMS still face two major problems: 1. It is difficult to obtain high quality electrophysiological signals due to the mismatch of mechanical properties and the lack of long-term stability of the electrode-biological interface. 2. The preparation conditions are harsh and complicated, and it is difficult to prepare array electrodes because of its large area and difficult patterning. Based on this, starting from the bio-electronic interface and focusing on the mechanical properties of PDMS regulated by Nonionic surfactants, a PDMS-based adhesive biological electrode was designed and prepared and used for electrophysiological signal detection, which provides an effective strategy for simple preparation of PDMS-based flexible electrode and high-quality electrophysiological signal acquisition. The main research contents include the following parts:

1. The regulation of the properties of adhesive PDMS biological substrate. Firstly, the effects of Nonionic surfactants with different HLB values on the mechanical and optical properties of PDMS were investigated. Among them, the maximum peeling force of PDMS (T-a-PDMS) biological substrate modified by Tween85 can reach 0.995 N. At 550 nm, the transmittance is 84%. After that, the effects of curing temperature and substrate thickness on the mechanical properties of T-a-PDMS biological substrate were discussed. Because of the dependence of Nonionic surfactant polarity on temperature, the optimum curing temperature range of T-a-PDMS biological substrate is 40℃-50℃. According to the mechanical model, the critical thickness of conformal contact between T-a-PDMS biological substrate and skin is 250 μm. When the thickness is less than 250 μm, the substrate can be conformally attached to the skin. After repeated washing, repeated peeling tests and two months of room temperature storage, T-a-PDMS biological substrates still have excellent adhesion properties.

2. Preparation and characterization of adhesive LIG/PDMS biological electrode. Based on T-a-PDMS biological substrate, combined with conductive material laser-induced graphene (LIG), adhesive LIG/PDMS bioelectrode was prepared. SEM, Raman spectra, XPS and other characterization methods proved that PI was successfully transformed into high-quality, porous three-dimensional graphene induced by laser. The results show that LIG has excellent electrical conductivity and the sheet resistance can be adjusted from 18.6 Ω/□ to 6.6 Ω/□. At the same time, the stable adhesion of T-a-PDMS biological substrate makes the electrode have low skin interface impedance. Cell experiments show that the electrode material has no cytotoxicity and has almost no effect on human epidermal cells, so it can be used to record electrophysiological signals of human epidermis.

3. The application of adhesive LIG/PDMS biological electrode. The biological electrode was used as the electrophysiological signal measurement electrode and compared with the LIG/PDMS electrode prepared on ordinary PDMS substrate. The signal quality was evaluated in terms of signal-to-noise ratio and baseline noise. Because of its stable electrode-skin interface, the electrode can obtain high quality electrophysiological signals. In addition, the electrode shows a strong signal recording ability in the detection of weak electrophysiological signals and multi-site electrophysiological signals.