Sensing implants that can be deployed by catheterization or by injection are preferable over implants requiring invasive surgery. However, present powering methods for active implants and present interrogation methods for passive implants require bulky parts within the implants that hinder the development of such minimally invasive devices. In this article, we propose a novel approach that potentially enables the development of passive sensing systems overcoming the limitations of previous implantable sensing systems in terms of miniaturization. In this approach implants are shaped as thread-like devices suitable for implantation by injection. Their basic structure consists of a thin elongated body with two electrodes at opposite ends and a simple and small circuit made up of a diode, a capacitor and a resistor. The interrogation method to obtain measurements from the implants consists in applying innocuous bursts of high frequency (≥1 MHz) alternating current that reach the implants by volume conduction and in capturing and processing the voltage signals that the implants produce after the bursts. As proof-of-concept, and for illustrating how to put in practice this novel approach, here we describe the development and characterization of a system for measuring the conductivity of tissues surrounding the implant. We also describe the implementation and the in vitro validation of a 0.95 mm-thick, flexible injectable implant made of off-the-shelf components. For conductivities ranging from about 0.2 to 0.8 S/m, when compared to a commercial conductivity meter, the accuracy of the implemented system was about ±10%.

中文翻译：

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基于体积传导电流的被动整流的可注射传感器。

可以通过导管插入或注射部署的感测植入物优于需要侵入性手术的植入物。然而，用于有源植入物的当前供电方法和用于无源植入物的当前询问方法需要植入物中的笨重的部件，这阻碍了这种微创设备的发展。在本文中，我们提出了一种新颖的方法，该方法有可能使无源感测系统的开发克服微型化方面以前的可植入感测系统的局限性。在这种方法中，将植入物成形为适合于通过注射植入的线状装置。它们的基本结构包括一个细长的细长体，在两端分别有两个电极，以及一个由二极管，电容器和电阻器组成的简单小电路。从植入物获得测量值的询问方法包括施加无声的高频（≥1MHz）交流电脉冲，该脉冲通过体积传导到达植入物，并捕获和处理这些脉冲后植入物产生的电压信号。作为概念验证，并为说明如何将这种新颖方法付诸实践，在此我们描述用于测量植入物周围组织电导率的系统的开发和特性。我们还将描述实施方式和 为了说明如何将这种新方法付诸实践，我们在这里描述了一种用于测量植入物周围组织电导率的系统的开发和特性。我们还将描述实施方式和 为了说明如何将这种新颖的方法付诸实践，我们在这里描述了一种用于测量植入物周围组织电导率的系统的开发和特性。我们还将描述实施方式和体外由现成的部件制成的0.95毫米厚的柔性可注射植入物的验证。对于电导率范围从约0.2到0.8 S / m，与商用电导率仪相比，所实现系统的精度约为±10％。