# Development of an Ergonomic Writing Assistive Device for Finger Pain Reduction in the Elderly
## 1 Introduction  
Today, literacy skills are required to adapt to a rapidly changing social environment. Literacy refers to the ability to read and write, but it is so important that it is essentially required for participation in social and cultural life [1]. In Korea, adult literacy education is provided to improve literacy skills. According to the National Institute for Lifelong Education and KOSIS (Korean Statistical Information Service), the elderly in their 60s and older comprise 95% of the illiterate population and 87% of the participants are in literacy education [1, 2]. The writing activity of literacy education can have a positive effect on cognitive function, depression, and social network in the elderly [3, 4]. However, as a consequence of aging, the body loses muscle strength and grip strength as muscle mass decreases [5, 6], and pain in muscles and joints increases along with the presence of musculoskeletal diseases [7], making writing more difficult. In an experiment comparing young adults and the elderly, the elderly took longer to write [8]. A slow writing speed lengthens writing time, and may cause excessive muscle contraction, resulting in pain [9]. The elderly sometimes use WADs (writing assistive devices) to reduce muscle pain in their fingers that can occur after writing for a long time. Existing WADs, however, have a weak holding power of the pen, which reduces writing efficiency. Furthermore, existing WADs actually increase the burden on other muscles (wrist, shoulder, and waist), making it difficult to write for a long time [10; 11]. Previous studies that conducted device development and performance evaluation to solve and improve the problems of existing WADs are as follows. [PERSON] and [PERSON] derived and developed design guidelines for WADs for children with crippled disorder [12]. Comparing the performance of their WAD against a normal pen, it was reported that, although writing accuracy improved, some children found it difficult to use because of the unfamiliar grip method, shape, and the uniform size of WADs. [PERSON] studied the potential use of a WAD for the elderly with osteoarthritis of the hand [13]. A new WAD used in this research had excellent pen fixing power as the pen and the assistance device were manufactured integrally. Additionally, the internal structure of this WAD, which is wrapped in latex, is made of vacuum powder, so it can be adjusted to suit the hand of the user. However, as a result of comparative experiments, the writing speed was slower when using the new WAD than the commercialized WAD. In addition, it was confirmed that there are disadvantages in comfort and durability compared with the commercialized WAD. Especially, in some cases, the pen was damaged during use owing to the weak durability of the manufacturing material. [PERSON] et al. developed a personalized WAD for patients with writer's cramp [14]. Using their WAD, writing ability was improved compared with normal pens. Additionally, in a previous study on the WAD design elements for people with spinal disorders, it was found that improvements such as grip method, shape, size, fixation power, and material were necessary [11]. We learned from previous studies that, when designing a WAD, the grip method, shape, size, durability, and shape of the finger should be considered. Moreover, in evaluating the usability of a WAD, the previous studies evaluated only subjective indicators such as writing accuracy, preference, and comfort. However, we also found that the biomechanical properties of the muscles of the hand and arm must be considered when using a WAD. Therefore, in this study, an ergonomic WAD was developed that solved the limitations of existing studies, and the usability of various subjective viewpoints was evaluated using QUEST 2.0 (Quebec User Evaluation of Satisfaction with Assistive Technology). In addition, to evaluate the biomechanical properties applied to the muscles of the hand and arm when using a WAD, muscle activity and finger pressure distribution were measured.