Multifunctional Flexible Piezoelectrics for Wearable Medical Devices.

到2021年，全球医疗可穿戴设备市场将达到121亿美元。在医疗保健技术中，智能可穿戴设备为诊断、治疗、患者监测和预防提供了附加值。糖尿病是最常见的慢性内分泌疾病之一，可以在生命的任何阶段发展，其发病率正在迅速增加。根据国际糖尿病联合会的数据，目前全球有4.15亿糖尿病患者，预计到2040年这一数字将增长到6.42亿，预计25年内将增长55%。糖尿病周围神经病变是糖尿病患者的常见并发症，其中由神经损伤引起的感觉丧失可使人们难以感觉到他们的脚何时处于皮肤破裂的风险中，这可导致脚溃疡形成。这些溃疡可能无法愈合，并随着时间的推移而感染;约30%的糖尿病足溃疡患者可能有下肢截肢的风险。目前的最佳实践建议患者进行日常监测他们的脚定期体检由训练有素的专家，这是耗时的。在这里，我们提出了一种新的自我供电的可穿戴多功能传感设备，监测病人的姿势的发展。当压力传感插件检测到临床上危险的足部压力时，就会发出光信号和声音警报，提示设备用户从足部的特定区域卸载压力。多功能设备将由柔性聚合物基底上的几层丝网印刷功能陶瓷油墨组成。磷光体层产生电致发光（EL）光，压电层产生声音，并且另外收集机械能并将其转换成EL光用于反馈。热电层收集热能并将其转换为电能。无铅铁电材料，如钛酸钡（BT）和钾钠钛酸（KNN）为基础的陶瓷，将被打印和介电，压电和铁电性能的特点。不同的荧光粉，如ZnS和ZnS：Cu将被制造，以实现最佳和均匀的光发射。将磷光体、压电和热电材料结合在一起，将产生一种压电-热电-电致发光装置，该装置通过外部机械能和热能的能量收集来同时发出声音和光。该项目与DST Innovations合作，DST Innovations是柔性材料印刷电子领域的专家公司。DST的重点是开发节能和环保的技术，以取代当今电子产品中使用的技术。该公司在开发用于大面积照明的轻质、低功耗和灵活的照明解决方案方面拥有专业知识，并将通过提供技术知识来支持该项目。该博士项目的主要目标如下：配制和测试无铅压电油墨（BT基，KNN）和磷光体油墨（ZnS）的印刷适性和性能配制和测试导电油墨以获得最佳电极结构使用丝网印刷制造多层器件。压电层和荧光粉层将单独印刷和组合印刷，有电极和没有电极。使用阻抗谱，压电，热释电，铁电，电致发光和表面粗糙度分析来表征物理和机电性能开发和测试自供电多功能可穿戴压电器件

The global market for medical wearable devices will reach $12.1 billion by 2021. In healthcare technologies, intelligent wearable devices provide an added value to diagnosis, treatment, patient monitoring and prevention. Diabetes is one of the most common chronic endocrine conditions that can develop at any stage of life and its incidence is increasing rapidly. According to the International Diabetes Federation, there are currently 415 million people worldwide with diabetes and this number is expected to grow up to 642 million in 2040, with an estimated 55% increase in 25 years.Diabetic peripheral neuropathy is a common complication for people with diabetes, where the loss of sensation caused by nerve damage can make it difficult for people to feel when their foot is at risk of skin breakdown, which can result in foot ulcers forming. These ulcers can fail to heal and become infected over time; around 30% of patients with a diabetic foot ulcer may be at risk of lower limb amputation. Current best practice recommends patients perform daily monitoring of their feet supported by regular physical examination by trained specialists, which is time-consuming.Here we propose the development of a novel self-powered wearable multifunctional sensing device that monitors the patient's posture. Whenever the pressure sensing inserts detect clinically dangerous foot pressure, a light signal and an audio alert are transmitted prompting the device user to offload the pressure from a particular region of their foot.The multifunctional device will be composed of several layers of screen-printed functional ceramic inks on a flexible polymer substrate. A phosphor layer generates electroluminescent (EL) light and a piezoelectric layer generates sound and additionally harvests mechanical energy and convert it into EL light for feedback. A pyroelectric layer harvests thermal energy and converts that to electrical energy. Lead-free ferroelectric materials, such as barium titanate (BT) and potassium sodium niobate (KNN) based ceramics, will be printed and the dielectric, piezo and ferroelectric properties will be characterised. Different phosphors such as ZnS and ZnS:Cu will be fabricated to achieve optimum and uniform light emission. Coupling of the phosphor, piezoelectric and pyroelectric materials will result in a piezo-pyro-electro-luminescence device with simultaneous sound and light emission powered by energy harvesting of the external mechanical and thermal energy.The project is in collaboration with DST Innovations, an expert company in printed electronics for flexible materials. The focus of DST is developing energy-efficient and environmentally safe technologies that can replace those used in today's electronic products. The company has expertise in developing lightweight, low powered and flexible lighting solution for large area lightings and will support the project by offering technical knowledge.The main goals of this PhD project are the following:Formulate and test the printability and performance of lead-free piezoelectric inks (BT-based, KNN) and phosphor inks (ZnS)Formulate and test the conductive inks for optimum electrode structureFabricate multilayer devices using screen printing. Piezoelectric and phosphor layers will be printed individually and in combination, with and without electrodes.Characterise the physical and electromechanical properties using impedance spectroscopy, piezoelectric, pyroelectric, ferroelectric, electroluminescence and surface roughness analysisDevelop and test the self-powered multifunctional wearable piezoelectric device