传感器技术是当今世界令人瞩目的一项高新技术，是实现国家物联网战略的核心基础。在国家工信部《信息通信行业发展规划(2016-2020年)物联网分册》关于深化物联网应用示范要求的背景下，数字式传感器因其可直接接入数字系统和抗干扰能力强的优点，已经成为物联网用传感器技术的热点研究方向之一。电子调谐式石英晶体传感器是一种以石英晶体串联探测电极为主要结构的谐振式数字传感器，它利用探测电极作为传感单元，基于石英晶体电子调频效应为响应原理，能够将由被测对象引起的探测电极参数变化转换为频率信号输出，具有灵敏度高、稳定性好和数字信号输出等诸多优点。本文综合运用理论分析和实验研究相结合的研究方法，对电子调谐式石英晶体传感器技术的相关理论进行了深入的研究，在此基础上，基于电子调谐式石英晶体传感器技术实现了对位移、盐溶液浓度以及湿度的检测应用。 本文的主要研究工作如下： (1)以石英晶体电容调频理论为基础，运用石英晶体扩展频偏理论，提出利用电感增敏的方法来提高电容调谐式石英晶体传感器的响应灵敏度。通过建立该传感器的等效电路模型，推导得到其电容-频率响应关系表达式。该表达式的数值计算结果表明，引入串联电感元件可有效提高石英晶体串联电容电路的电容-频率响应灵敏度，针对实际电路的测试结果也进一步证明了这一结论。在此基础上，结合平面电容探头，制作了一种基于电感增敏的高灵敏电容调谐式石英晶体位移传感器，其位移检测灵敏度能达到传统电容调谐式石英晶体传感器的三倍。本研究从电路优化的角度，为提高电容调谐式石英晶体传感器响应性能提供了一种切实可行的方法。 (2)针对石英晶体串联电感电路的电感调频特性进行了研究，在建立等效电路模型的基础上，给出了该电路的阻抗表达式，进一步结合振荡电路谐振理论，推导得到了该电路的频率响应表达式。针对实际电路的测试结果与该表达式的数值计算结果相符，有效验证了该表达式的合理性，为构建电感调谐式石英晶体传感器奠定了理论基础。以此为基础，结合平面电感线圈和电涡流理论，开发了一种电感调谐式石英晶体微位移传感器，并对该微位移传感器的相关特性展开了实验测试研究，测试结果表明，该传感器具有位移分辨力高和频率稳定性好的优点。 (3)利用石英晶体串联电感电路具有电感-频率响应的特性，结合平面螺旋电感探头，构建了一种电感调谐式石英晶体盐溶液浓度传感器，可以将盐溶液浓度信息直接转换为传感器的谐振频率值。实验研究了该传感器对硫酸铜溶液的响应性能，结果表明，在0～10mM范围内，该传感器对不同浓度的硫酸铜溶液具有线性响应，响应灵敏度可达50 Hz／mM。此外，该传感器还具有高稳定性和快速响应和恢复性能，响应和恢复时间均小于1秒，使得该传感器具有在线检测的应用潜力。 (4)通过在IDE表面涂覆COQD薄膜，制备了一种高灵敏的IDE-PQCR数字频率式湿度传感器，实验研究了所制备的湿度传感器的湿敏响应特性、湿滞特性以及动态响应和恢复特性。实验结果表明，GOQD薄膜修饰的IDE-PQCR湿度传感器具有高灵敏的湿度-频率响应性能，其响应灵敏度为81 Hz／％RH，这一结果是基于常规GO薄膜修饰的IDE-PQCR湿度传感器的四倍。在深入分析GOQD薄膜内部水分子渗透作用机理的基础上，结合IDE-PQCR电路调频理论，提出GOQD薄膜修饰的IDE-PQCR湿度传感器是依赖于阻抗调频响应原理的，解释了传感器的高灵敏响应机制。 关键词：数字传感器；谐振式传感器；石英晶体；电子调频；位移检测；盐溶液浓度检测；湿度传感器；氧化石墨烯量子点

 Sensor technology is a high and new technology in the world, and an important part of the Internet of Things (IoT). In the context of deepening the application demonstration of the IoT, as requested in the IoT fascicule of development plan for information and communication industry (2016-2020) issued by the Ministry of Industry and Information Technology (MIIT), digital sensor has become one of the hot research directions of IoT sensor because of its advantages of direct access to digital system and anti-interference ability. The electronic tuned quartz crystal sensor is a resonant digital sensor with a quartz crystal and a detection electrode in series. Based on quartz crystal electronic frequency modulation effect and using the electrode as a sensing unit, the detection electrode parameter variation caused by the measured object can be converted into frequency signal output characterized by high sensitivity, good stability, digital signal output, and many other advantages. Combining theoretical analysis and experimental research, this thesis takes an exhaustive research on the electronic tuned quartz crystal sensor technology, and achieves the detection of displacement, salt solution concentration and humidity based on the electronic tuned quartz crystal sensor technology. The main innovative works in this thesis are summarized as follows: (1)Based on capacitance frequency modulation theory and frequency deviation theory of quartz crystal, a capacitance tuned quartz crystal sensor with inductance sensitization is proposed. The equivalent electrical model of the sensor is established, and the capacitance-frequency response expression of the circuit is derived. Both the numerical simulation results and the actual circuit test results show that the capacitance-frequency response sensitivity of the capacitance tuned quartz crystal sensor can be enhanced by introducing an inductance element. On this basis and combined with a planar capacitance probe, we have designed a highly-sensitive capacitance tuned quartz crystal displacement sensor. The sensitivity of its displacement detection is three times that of the conventional capacitance tuned quartz crystal displacement sensor. This study provides a practical method for improving the response performance of capacitance tuned quartz crystal sensors from the perspective of circuit optimization. (2)The inductance frequency modulation effect of a quartz crystal series inductor circuit is studied. On the basis of establishing the equivalent circuit model, and combining the resonance theory of oscillation circuit, the inductance-frequency response expression of the equivalent circuit is derived. The numerical simulation results of the expression coincide with test results in view of the actual circuit, which demonstrates the rationality of the expression. The theoretical basis of inductively tuned quartz crystal sensor is established. Combining with a plane inductance coil and the eddy current theory, an inductance tuned quartz crystal micro-displacement sensor has been realized. Relevant test results show that this sensor has a high displacement resolution and a good frequency stability. (3)Taking advantage of the inductance-frequency response characteristics of the quartz crystal series inductor circuit, and combining with a planar spiral inductance probe, an inductance tuned quartz crystal salt solution concentration sensor is constructed and proposed. Salt solution concentration information can be directly converted into resonant frequency of the sensor. The experimental results show that the sensor has a linear response to different concentrations of copper sulfate solution, and the response sensitivity can reach 50 Hz/mM. In addition, the sensor is characterized by fast response and recovery performance, and the response and recovery time is both less than one second. This work implements a high performance salt solution concentration sensor with digital frequency output. (4)By utilizing GOQD materials as humidity sensitive film, a highly-sensitive IDE-PQCR humidity sensor with digital frequency output was constructed. The sensor's humidity sensing characteristics, such as response property, hysteresis property and dynamic response and recovery property, are studied. Experimental results show that the proposed GOQD based IDE-PQCR humidity sensor has a high sensitivity which is four times of the GO based IDE-PQCR humidity sensor. Considering the modulation theory of IDE-PQCR circuit and the infiltration mechanism of water molecules in GOQD film, an impedance-frequency modulation mechanism is presented to explain the humidity sensing principle of the proposed sensor. This work provides a new research idea for building highly-sensitive digital humidity sensors. Keywords: Digital sensor; resonantor sensor; quartz crystal; electronic frequency modulation; displacement detection; salt solution concentration detection; humidity sensor; graphene oxide quantum dots.