## 1 Introduction  
Whether involving a brand-new product or improving and updating an existing one to evolving and changing demands, the product design process is need-driven. New product innovation can be manifested as market-pull (filling customer needs including improving ergonomics and usability), technology-push (improving technological features such as accuracy, speed, etc. due to scientific breakthrough), or design-driven innovation (creating a new look-and-feel as part of a new branding process) [1].  
Every product is unique; consequently, each design process requires different tools, advisors, and research methods relevant to its specific needs. A structured methodology hopefully leads to a structured process and an optimal product.  
Numerous product management and development methodologies have evolved over the years to initiate an effective product design process that meets changing market needs and demands. Whereas engineering research and methodologies have existed since the 19 th century, design became a topic of research only towards the end of the 20 th century [2]. Some of the methodologies focus on a narrow part of the process, aiming to generate innovative solutions and produce a great number of ideas and concepts [3, 4]. These include methods for exchanging knowledge in multidisciplinary product development teams [5], solving ergonomic design and usability issues [6], examining the aesthetic aspects of the product [7], or focusing on the design of particular objects and demands such as soft wearable devices, sports equipment, or emergency ventilators [8, 9, 10]. Other methods take a more holistic approach and observe the process throughout its length and breadth [11]. We developed and formulated the Functionality, Usability, Look-and-Feel, and Evaluation (FULE) methodology based on ten years of experience in developing various medical devices and participating in many design processes. This method evolvedfrom the necessity to create a structured methodology that focuses on the designer's role and responsibility in the medical system product development process. More than other design fields, medical device design presents significant challenges related to safety, ease of use, and appearance. Nevertheless, industrial design is often perceived as redundant in the medical device development process that usually focuses on technological aspects.  
While developers and engineers aim to optimize for functionality, the designer aims to optimize for user experience. These two goals must go hand in hand from the beginning of the process to achieve success. FULE methodology guides the designer in this complex multidisciplinary process and provides tools for better team communication. The need for this new methodology is derived from various obstacles encountered during the development process (including inadequate designer-team member communication, decision-making difficulties, unsuitable chosen aesthetics, etc.) that resulted in a waste of time and, hence, money. Using failure analysis at the end of every design project helped us analyze obstacles, find solutions, and determine rules. These were then applied in the next projects. The result was a clear guide that leads the designer through the whole procedure, starting at the beginning of a process and ending only after the product is already in use by real users. FULE structures the industrial designer's path to explore and develop design solutions step-by-step using continuous formative assessments in every phase with a final summative assessment that evaluates the process, the outcome, and the methodology for future adjustments. FULE provides visual means to discuss alternatives and conflict demands and helps the designer communicate with other team members.  
This paper presents an overview of the FULE methodology phases, followed by a case study that illustrates implementation of the FULE methodology.