We present the development of a novel smart ink pen instrumented with force and motion sensors designed for the quantitative and ecological assessment of daily-life handwriting. This work aims at testing the pen’s sensors and algorithms and the use of the smartpen to detect age-related changes in writing and tremor parameters during daily-life handwriting. A comparison against reference instruments was carried out to validate the pen tip force during static and dynamic conditions, the pen’s tilt angle, and the algorithm for the segmentation of the force signal into strokes. The smartpen was tested on 43 healthy adults divided into three age groups (young, middle-old, and old) during unconstrained handwriting on paper. The validation of the pen’s sensors and algorithms reported excellent results. A solid test–retest reliability was found in the writing and tremor indicators extracted from both young and old adults. As for the age-related analysis, the older age groups were characterized by an increase of temporal writing measures, a more uniform writing pressure, and more repetitive and predictable tremor oscillation components. The greatest accomplishment of our smart ink pen is the ability to combine the advantages of the digitizing tablet technology with the natural “feel,” the ease of use, and the ecological validity of the traditional pen-and-paper approach. The proposed solution represents an important step toward a simple, ecologically valid, reliable quantitative assessment of daily-life handwriting. Our smartpen is particularly suitable for daily-life telemonitoring applications in a number of important health-related fields.

中文翻译：

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一种智能墨水笔，用于对书写和震颤特征的年龄相关变化进行生态评估

我们展示了一种配备力和运动传感器的新型智能墨水笔的开发，该传感器专为日常生活笔迹的定量和生态评估而设计。这项工作旨在测试笔的传感器和算法，以及使用 smartpen 检测日常生活手写过程中与年龄相关的书写和颤抖参数的变化。与参考仪器进行了比较，以验证静态和动态条件下的笔尖力、笔的倾斜角度以及将力信号分割为笔划的算法。智能笔在 43 名分为三个年龄组（青年、中年和老年）的健康成年人身上进行了测试，他们在纸上进行了不受约束的手写。笔的传感器和算法的验证报告了出色的结果。在从年轻人和老年人中提取的写作和震颤指标中发现了可靠的重测信度。至于年龄相关分析，年龄较大的年龄组的特点是时间书写量度增加，书写压力更均匀，以及更多重复和可预测的震颤振荡成分。我们智能墨水笔的最大成就是能够将数字化手写板技术的优势与传统纸笔方式的自然“感觉”、易用性和生态有效性相结合。所提出的解决方案代表了朝着对日常生活笔迹进行简单、生态有效、可靠的定量评估迈出的重要一步。我们的 smartpen 特别适用于许多重要的健康相关领域的日常生活远程监控应用。