Printable giant magnetoresistive sensors with high sensitivity at small magnetic fields

在小磁场下具有高灵敏度的可印刷巨磁阻传感器

• 批准号: 407555984
• 负责人: Professor Dr.-Ing. Christoph Leyens
• 金额: --
• 依托单位: Institut für Ionenstrahlphysik und Materialforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/407555984?language=en
• 关键词: Printable; giant; magnetoresistive; sensors; sensitivity

Printed electronics are about to revolutionize the field of conventional electronics offering low-cost, large area and high-throughput production. By adding a magneto-sensitive element to the family of printable electronics, we envision the realization of energy efficient contactless switches for intelligent packaging or postcards as well as smart and protective clothes (e.g., for firefighters, athletes) offering the in-cloth integrated navigation and position tracking modules. Although highly demanded, high-performance printable magnetic field sensors relying on giant magnetoresistive (GMR) effect are not available manly due to the lack in the fundamental understanding of the magnetoresistive effects in a GMR powder mixed with a polymeric binder solution.First proof-of-concept realizations of printable GMR sensors are reported by us. However, the optimization of the sensors is based on empirical approaches, which do not allow us to achieve strong sensor responses in the range of small magnetic fields, e.g. <10 mT as needed for the application in consumer electronics and wearables. It can well be that the performance of printed sensors in the small fields region is fundamentally limited by the randomization effects due to the electron transport through percolated GMR flakes. Alternatively, it can be that we do not understand the role of the size of the GMR flakes on the GMR response of printed sensors. Is there a limitation on the flake size when the GMR response will disappear due to the mechanical impact upon ball milling? What is the impact of the ball milling on the magnetic properties of the GMR powder? In this project we address these important fundamental issues, aiming to boost the performance of printed GMR sensors further. Our preliminary work indicates that the magnetron sputter deposition used to fabricate the GMR powder might be not optimal to achieve sensitivity at small magnetic fields. In this project, we will prepare GMR powder using complementary approaches: (i) magnetron sputter deposition and (ii) ion beam sputtering. In contrast to the magnetron sputter deposition, the ion beam sputtering allows to produce GMR multilayers revealing (i) the absence of hysteresis and (ii) superior linearity even at small magnetic fields. This performance is very attractive for the realization of high-performance flexible and printable magnetic field sensors. The fabrication of GMR stacks using ion beam sputtering is not as well established as using magnetron sputter deposition. Therefore, the fundamental understanding of the magnetization processes in ion-beam sputtered magnetic/nonmagnetic sandwiches is still lacking. We will close this gap and investigate what is the physical reason behind the experimentally observed remarkable linearity and absence of hysteresis of the GMR response down to small magnetic fields of GMR stacks prepared by ion-beam sputtering.

印刷电子产品即将彻底改变传统电子产品领域，提供低成本、大面积和高产量的生产。通过在可印刷电子产品系列中添加磁敏元件，我们设想实现用于智能包装或明信片以及提供布内集成导航的智能防护服（例如消防员、运动员）的节能非接触式开关和位置跟踪模块。尽管需求量很大，但由于缺乏对与聚合物粘合剂溶液混合的 GMR 粉末中的磁阻效应的基本了解，依赖于巨磁阻 (GMR) 效应的高性能可印刷磁场传感器目前还无法实现。 -我们报告了可打印 GMR 传感器的概念实现。然而，传感器的优化是基于经验方法，这不允许我们在小磁场范围内实现强传感器响应，例如磁场。 <10 mT，满足消费电子产品和可穿戴设备应用的需要。印刷传感器在小场区域的性能很可能从根本上受到随机化效应的限制，该随机化效应是由于电子通过渗透 GMR 薄片的传输而产生的。或者，也可能是我们不了解 GMR 薄片的尺寸对印刷传感器 GMR 响应的作用。当 GMR 响应因球磨的机械冲击而消失时，薄片尺寸是否有限制？球磨对GMR粉末的磁性能有何影响？在这个项目中，我们解决了这些重要的基本问题，旨在进一步提高印刷 GMR 传感器的性能。我们的初步工作表明，用于制造 GMR 粉末的磁控溅射沉积可能不是在小磁场下实现灵敏度的最佳选择。在这个项目中，我们将使用互补方法制备 GMR 粉末：(i) 磁控溅射沉积和 (ii) 离子束溅射。与磁控溅射沉积相反，离子束溅射可以产生 GMR 多层，显示出 (i) 不存在磁滞现象，并且 (ii) 即使在小磁场下也具有出色的线性度。这种性能对于实现高性能柔性可印刷磁场传感器非常有吸引力。使用离子束溅射制造 GMR 堆栈的技术并不像使用磁控溅射沉积那样成熟。因此，仍然缺乏对离子束溅射磁性/非磁性三明治中磁化过程的基本了解。我们将缩小这一差距，并研究通过离子束溅射制备的 GMR 堆栈在小磁场下实验观察到的 GMR 响应的显着线性和无滞后现象背后的物理原因。