Abstract：
Direct and precise monitoring of intracranial physiology holds immense importance in delineating injuries, prognostication and averting disease1. Wired clinical instruments that use percutaneous leads are accurate but are susceptible to infection, patient mobility constraints and potential surgical complications during removal2. Wireless implantable devices provide greater operational freedom but include issues such as limited detection range, poor degradation and difficulty in size reduction in the human body3. Here we present an injectable, bioresorbable and wireless metastructured hydrogel (metagel) sensor for ultrasonic monitoring of intracranial signals. The metagel sensors are cubes 2 × 2 × 2 mm3 in size that encompass both biodegradable and stimulus-responsive hydrogels and periodically aligned air columns with a specific acoustic reflection spectrum. Implanted into intracranial space with a puncture needle, the metagel deforms in response to physiological environmental changes, causing peak frequency shifts of reflected ultrasound waves that can be wirelessly measured by an external ultrasound probe. The metagel sensor can independently detect intracranial pressure, temperature, pH and flow rate, realize a detection depth of 10 cm and almost fully degrade within 18 weeks. Animal experiments on rats and pigs indicate promising multiparametric sensing performances on a par with conventional non-resorbable wired clinical benchmarks.
摘要：
颅内生理学的直接和精确监测在描绘损伤方面具有极其重要的意义。预测和避免疾病1。使用经皮导线的有线临床仪器准确，但容易感染，移除期间患者的活动限制和潜在的手术并发症2.无线植入式设备提供更大的操作自由度，但包括有限的检测范围等问题，在人体中降解不良和尺寸减小困难3。这里我们介绍一种注射剂，用于颅内信号超声监测的生物可吸收和无线复结构化水凝胶（metagel）传感器。metagel传感器的尺寸为2×2×2mm3，包含可生物降解和刺激响应性的水凝胶以及具有特定声反射光谱的周期性排列的空气柱。用穿刺针植入颅内间隙，metagel响应于生理环境变化而变形，引起反射的超声波的峰值频率偏移，可以通过外部超声探头无线测量。metagel传感器可以独立检测颅内压，温度,pH和流速，实现10厘米的检测深度，并在18周内几乎完全降解。大鼠和猪的动物实验表明，有希望的多参数传感性能与常规的不可吸收的有线临床基准相当。
