一种具有双工作模式的触觉传感器的研究

Tactile sensors could find broad applications in robotics, artificial intelligence and biomedical and healthcare engineering. Pressure image capturing device is one of the main strategies towards artificial tactile sensation. However, a dynamic tactile sensing based on pressure image capturing requires an extremely high frame frequency. It results in a large amount of information and causes an overburden for the information transfer and processing. A nano-generator type tactile sensor has been proved to be an effective way to capture dynamic tactile information without frame frequency limitation. We propose a suspended electret gate thin-film transistor (SEGTFT) as a convertor, which combines a tribo-electrical nano-generator with thin-film transistor. An array of SEGTFTs can serving as both a nano-generator type tactile sensor and a pressure image capturing device. As a nano-generator type tactile sensor, it translates the texture and sliding motion information into actively outputted electric pulses. A pressure image can be readout from the current change of the array of active channels. The frame frequency requirement could be significantly lowered down because of the dual function of the tactile sensor. The actively outputted electric pulses by the nano-generator type tactile sensor could also serve as an awaken signal for the pressure image read out circuit. In this way, the whole device could stay at a standby model, which is highly desired for a net of distributed tactile sensor for an intelligent robot. Through this project, we may pursue a promising new way towards practical tactile sensation with both static and dynamic sensing.

触觉传感器在人工智能和医疗保健等领域有着重大应用需求。基于压力分布图像的触觉传感是当前触觉模仿的主要思路。但是其对动态过程的捕捉依赖高扫描帧频，数据量大，传输和处理困难。纳米发电机型触觉传感器对动态触觉信息敏感，且主动输出信号，不需扫描。为此项目提出一种新型力电转换器（悬空驻极体栅极薄膜场效应管：SEGTFT），并通过其阵列化将压力图像传感器和纳米发电机型触觉传感器结合，实现发电机触觉传感和压力分布触觉传感两种工作模式。发电机触觉传感模式由SEGTFT感应电极上的电脉冲提供动态触觉信息，可捕捉振动、滑动和触碰分离等动态信息；压力分布触觉传感模式由沟道电流变化提供压力空间分布信息，不关注动态信息，故可大幅降低扫描频率，减少信息量。通过电脉冲唤醒压力分布扫描电路，可实现“事件驱动”的极低功耗工作模式，有力推动分布式触觉传感器应用技术的发展。项目研究将为完整触觉功能的实现提供一条全新的技术思路。

项目研究主要集中于将摩擦电纳米发电机与薄膜晶体管（TFT）通过悬空扩展栅极集成，从而实现了一种同时具有静态和动态力检测能力的触觉传感器。为此项目围绕摩擦电纳米发电机（TENG）的结构和材料优化以及TFT器件工艺及性能优化两个方面开展了系统的研究。前期研究实现了一种基于单电极TENG的脉搏传感器，获得了手腕脉搏的典型波形。充分验证了悬空栅极结构作为扩展栅极结构的可行性。通过将纳米发电机与石墨烯场效应晶体管结合，初步实现了触觉传感器的双工作模式。为了进一步提高器件的响应和信噪比，项目制备了高开关比的IGZO-TFT，通过大量的工艺优化，包括基于超临界流体的后处理工艺，获得了具有8个数量级的开关比，为静态力的感知提供了有力支撑。设计研制了一中基于IGZO-TFT的悬空驻极体栅极薄膜场效应管，并利用离子凝胶大幅提高了摩擦电荷对TFT沟道的耦合电容，从而显著提高了器件的动静态力的响应度，为双工作模式触觉传感器的实现奠定了坚实的基础。在此基础构建了一款4×4的阵列型器件，在不同力的作用下，沟道电流变化范围达两个数量级，为高精度的力的解析奠定了基础。初步获得了触觉压力的空间解析能力，且其触觉传感单元具备静态力和动态力的双工作模式，实现了项目的预期研究的目标。为未来高解析度智能柔性触觉传感器的发展奠定了基础。