A glimpse into the world of human-centered technology development

USE-Ing. and IRNAS: Partnership for User-Centric, Cost-Effective, and Innovative Solutions in Global Markets

Collaboration for the Development of Better, User-Centric Devices

IRNAS and USE-Ing. have officially announced their partnership to develop innovative and user-centric solutions for various industries. The two companies are pooling their resources to promote sustainable and long-lasting solutions that are tailored to the needs and workflows of users.

With a broad spectrum of industries and sectors, including consumer goods, medical technology, and security technology, USE-Ing. and IRNAS will jointly shape the future of the industry.

Experienced team develops user-centric solutions with IRNAS partnership

USE-Ing. is composed of an interdisciplinary research and design team of experienced usability engineers, psychologists, HMI, and UX designers. This team has developed a deep understanding of users and their needs in their professional everyday life and is capable of identifying and addressing technological challenges to ensure a better user experience.

“The partnership with IRNAS enables USE-Ing. to have a more agile and reliable solution creation process,” says Marcus Jenke, Managing Director of USE-Ing. “The experienced collaboration with such a highly professional and motivated team allows us to focus more on overcoming the challenges that come with designing the most user-friendly and pleasant user interaction possible, without stumbling over the hurdles of technical implementation. True user acceptance is only sustained in the long term if thoughtful ergonomics and usability are maintained and can be found in the final product on the market.

The unique combination of in-house manufacturing and multidisciplinary engineering experts with comprehensive experience in building devices using rapid prototyping methods allows IRNAS to develop cost-effective and time-optimized solutions for various industries. The solution design that enables an intuitive user experience significantly increases satisfaction and product success.

“The partnership with USE-Ing. enables IRNAS to offer an overall better development service,” says Luka Banović, Product Development Lead at IRNAS. “Working with a company that specializes in engaging with users at such a profound level like USE-Ing. makes our life as a product development house much easier. Well-thought-out products last longer and are not so quickly outdated. This aligns perfectly with the vision and values of IRNAS, not just to manufacture more devices, but to keep the devices that come to market as relevant as possible for as long as possible, thereby creating the greatest added value.

Both our companies are based in Europe, but they offer their products and services on the global market, assisting some of the largest companies in the most demanding sectors in the introduction of innovative solutions.

About the companies USE-Ing. and IRNAS

USE-Ing. GmbH is a German human factors engineering and design service company with the mission to develop technology for and especially with users. Since 2018, USE-Ing. has become a renowned provider of professional services in the fields of human-centered product development, UX/UI design, ergonomics, usability optimization, and user-centered innovation. Involving real users at the right time and in the right way in the product development cycle is our distinguishing feature in the market. In the context of digitalization, automation, and demographic change, we support industrial companies from medical technology, aviation, and mechanical engineering in the user-friendly design of products. That’s why USE-Ing. recruits professional users who co-design and evaluate high-tech products throughout the entire development process, thus ensuring that “the right thing is built before it’s built.” 

IRNAS is a custom hardware development company based in Maribor, Slovenia. Since 2011, IRNAS has evolved into a visible, well-established design house covering many industrial areas. IRNAS offers electronics engineering, firmware development, software development, prototyping, and automated testing, as well as design for manufacturing and production management. With its constantly evolving in-house production capabilities, IRNAS ensures that it remains one of the fastest design and prototyping companies in this part of the world. IRNAS is one of the few EU-based design partners of Nordic Semiconductor and develops specialized solutions with BLE and mobile connectivity. In the past two years, IRNAS has also focused on becoming an expert in the integration of machine learning in devices. Their expertise in this area has been further advanced through a development partnership with Edge Impulse.

We are happy to support you holistically and user-centered in your development process. If you are interested, our experts are at your disposal with advice and action. Get in contact


Here you can find the link to the article at IRNAS:

Human Factors & Usability Engineering for Medical Products

With usability and user interface evaluations for user-centered medical devices

Since the introduction of the Medical Device Regulation (MDR), the examination of usability has become a focus for manufacturers of medical devices. At the heart of the so-called human factors or usability engineering process are user interface evaluations of medical products with medical professionals.

Medical progress and the innovative power of medical technology developers lead to an increasing number of interaction processes between people and technical, stationary, as well as ambulatory systems; from the perspective of the medical user as well as the treated patient. Here, the patient is usually not the user of the device, which is why medical devices typically have two interfaces to people. This interaction relationship represents the human-machine system, in which the system elements patient, doctor (or nurse), and machine are related to each other through interactions.

Usability-Engineering Schema zur medizintechnischen Mensch-Maschinen-Interaktion
Basic scheme of medical human-machine interaction

Due to the increasing use of innovative technical systems, new requirements arise from the user’s point of view in terms of safe, effective, efficient, and satisfactory operation of medical technology. The collection, implementation, and validation of these so-called usage requirements, alongside the design of user interfaces (User Interfaces) and their evaluation, are the focus of the “Usability Engineering Process”. In the development of medical devices, in addition to these components known from “User Centered Design,” the risk management of use-related risks (Use-related Risk Assessment) is an essential aspect.

Regulatory and standard requirements of the Usability Engineering Process

The establishment and implementation of a Usability Engineering Process and the documentation of all activities in a Human Factors or Usability Engineering File are part of the regulatory requirements for manufacturers of medical devices in the context of medical device approval. The normative references for usability engineering form, from a German perspective, DIN EN 62366-1:2021 and IEC/TR 62366-2:2016. The American Food and Drug Administration (FDA) raises additional regulatory requirements and presents them in its guideline document FDA-2011-D-0469 (Applying Human Factors and Usability Engineering to Medical Devices). Further requirements apply for China and the UK.

From the uss specification to user requirements engineering to use risk analysis

The specification of the application (Use Specification) represents the starting point of the Usability Engineering Process. This includes, among other things, the intended medical indication, the specification of user groups (User Profile), and the specification of all relevant usage environments. The specification of the application (Use Specification) already influences the later evaluation activities, for example, in the selection of representative test participants or test environments for the summative usability evaluation. The identification of user tasks and requirements in empirical studies of the usage context (User Research & Workflow Analyses) forms the bridge to the subsequent steps of use risk (Use-related Risk Assessment) and user requirements management (User Requirements Engineering). In the risk management process, use-related risks are analyzed and assessed based on task models. In the requirements management, the requirements necessary for the design of the human-machine interface (User Interfaces) are derived from the needs.


„Risk and requirements management processes represent the collaborative processes of usability engineering. If a close interlocking is achieved here, many synergistic effects for the medical device development process can be achieved. Do you want to align your medical device development process user-centrically? Our experienced experts are happy to support you.“

User Interface Design

The subsequent phases of design and evaluation are based on risk and requirement considerations. In the User Interface Design phase, all human-product interfaces (User Interfaces) are specified within the User Interface Specification and designed using prototyping methods. Depending on the nature of the medical device to be developed, various prototyping methods can be used. For example, 3D printing and laser cutting methods are suitable. The assurance of usability (Usability) of the developed User Interface prototypes is done using targeted usability evaluation methods.

User Interface / Usability Evaluationen

Usability evaluations form the heart of the Usability Engineering Process and must be planned early on. Here, the scope, type, and timing of the evaluation methods must be adapted to the complexity of the medical device to be evaluated, not only to prove the regulatory obligation of safe and effective handling but also to enable the actual added value, the desired optimization of human-product interaction. Usability evaluation methods can be divided into inspection and user test methods.

Inspection methods are carried out by usability professionals and mostly involve checking compliance with heuristics or design guidelines. Here, experienced experts check the user interfaces of the medical device for conformity or deviation with existing and recognized guidelines. In the context of medical device development, thinking through operating procedures (Cognitive Walkthrough) is also used as an inspection method.

In contrast, the second group of methods, the user test methods, follows an empirical, user-based approach. For this purpose, it is necessary to simulate the usage context sufficiently in the usability lab and to carry out observations and interviews with users representative of the respective medical device. The gold standard test method is the Usability Test, an evaluation of usability with users based on simulated task scenarios (Test Cases), usually with participant observation.

Medizintechnischer Usability-Test
Observation and documentation of a medical usability test

In the Usability Engineering Process for medical devices, methods from both groups are described in the normative references. Since inspection methods involve less implementation effort, they are recommended for early phases when the user interface is not yet sufficiently concrete for a Usability Test. When which method is used must be determined in the User Interface Evaluation Plan at the beginning of the design activities. Crucial are the early planning and methodically correct implementation of the evaluations.


„For usability tests, there are numerous methodological aspects that can be varied (e.g., remote-inhouse / synchronous-asynchronous), so that in principle ‘the standard usability test’ does not exist, but an individual test plan must be made depending on the specifics of the medical device to be tested. Are you facing the challenge of planning a medical usability test? Our experienced experts are happy to support you.“

If evaluations are carried out accompanying development, they are called formative evaluations. Here, the focus is on identifying optimization potentials of the human-medical product interaction and their design-technical reflection in the development process. The normative references recommend conducting several formative evaluations. Depending on the complexity, novelty, and risk profile of the user interface, two to three formative evaluations are advised.

At the end of the medical device development process, manufacturers are obliged to prove the safe and effective use of their medical device. This is done within the framework of summative usability validation or evaluation. The summative evaluation includes a normatively determined type of planning (Evaluation Plan) and documentation (Evaluation Report).


Medical Human Factors & Usability Engineering serves both to meet regulatory requirements and to identify market-differentiating optimization potentials. In this respect, the interlocking of usability evaluations with the application specification (Use Specification), risk management (Use-related Risk Assessment), and requirements management (User Requirements Engineering) is of the utmost importance and should be anchored interdisciplinary in the entire development team to maximize the benefits.

Do you need support in implementing your medical usability activities? Our USE-Ing. experts are ready for you.

Standards & References

User-Centered Development of Hand-Operated Tools and Equipment

User-Centered design of handheld tools

Understanding and properly applying the principles of technical ergonomics and usability

The market for hand-operated tools, from electric leaf blowers to vacuum-mop devices to hand drills, is highly competitive. While German-speaking manufacturers could defend market shares through technical performance a decade ago, international competitors are increasingly catching up in this regard. One of the most promising market differentiation potentials for the future is the user-centered development and design of work tools.

The design of human-tool interfaces, such as handles, operating and display elements, and innovative interaction concepts in the form of gesture and voice controls, are the focus and crucially determine comfortable and intuitive handling. However, for this product class, it is also essential to ensure safe handling for users even in the most extreme working conditions, such as dirt, temperature, or moisture. Manufacturers face the fundamental challenge of systematically identifying user needs from the start, translating these into technically specifiable usage requirements (User Requirements), prototyping them in the form of suitable human-machine interfaces, and ultimately evaluating them with real and representative end-users. These basic steps of user-centered product development should be iterated as quickly as possible according to DIN EN ISO 9241-210. The targeted integration of these sub-processes into the overall technical product development process is also demanding. The basis of user-centered work tool technology is provided by technical ergonomics, the approaches of usability (Engl. Usability), and suitable methods of interface prototyping.

Bedienung einer Bohrmaschine

Ergonomic fundamentals of work tool design

According to Schmidtke, “ergonomics is a scientific discipline whose object is the study of human interaction with technical systems”. This also implies the design and development of methods necessary for this research. Technical ergonomics, as further divided by Maier and Schmid, can be divided into macro and micro ergonomics. Macro ergonomics is based on a spatial ergonomics and height grid corresponding to body sizes, defining areas of visual and grasping spaces. Micro ergonomic content concerns the shape, color, graphic, and material design of control elements and graphical user interfaces. The ergonomic design of human-work tool interfaces is based on user-centered measures of anthropometry and the doctrine of comfort angles.

Anthropometric measurement conception

According to Schmidtke, anthropometry is the sub-discipline of anthropology that measures and statistically processes body measurements and proportions, as well as gender-, age-, region-, and socio-specific differences, and interprets them application-oriented if necessary. [2] Percentiles are mostly used for anthropometric data. This information indicates the percentage of the population group studied that falls below or exceeds a certain measurement. The 50th percentile corresponds to the median. For ergonomic designs of human-machine interfaces of hand-operated tools, besides the 50th percentile of the relevant body measure, usually the 5th percentile (female) and the 95th percentile (male) are used. It can be assumed that all users whose body measurements fall between these boundary percentiles can use the resulting product ergonomically satisfactorily.

Comfort angle doctrine

Comfort can be defined as subjectively experienced well-being in a given environment or simply through the absence of discomfort. The measure of comfort or discomfort is especially relevant in the user-centered design of hand-operated tools concerning body posture and the position of body parts or joints during operation. [2] From this, the definition of comfort angles as the angles between body parts that are subjectively perceived as pleasant arises.

Failure to maintain comfort angles results in forced postures in the form of unphysiological body postures forced by working conditions. These lead to fatigue and muscle pain after a longer duration due to static holding work. In addition, the perceived level of strain increases, which is the result of psychophysiological reactions of humans to external stresses.

For the design of an ergonomic gripping and operating posture of hand-held devices, the joint chain from the clavicle joint through the shoulder joint and elbow joint to the wrist joint is particularly relevant. In addition to the maximum movement angles, the comfort areas for the upper body and the hand-arm system are important features for a user-friendly design of hand-held products.

Veranschaulichung der Greif- und Bedienhaltung anhand eines Laubbläsers hinsichtlich der Menschzentrierten Entwicklung

Rapid prototyping of physical human-machine interfaces of hand-operated devices

Once the human-machine interfaces have been analyzed and conceptualized using ergonomic methods, the next step is to realize them in prototype form to make the handling and operation tangible for users. Depending on the type of interface to be designed (Engl. Interface), different methods are effective. For example, modular or plug-in systems are suitable for manipulation elements such as guide handles to estimate the basic grip and grasping surface layout. For controls and detailing of handles, plastiline or clay can be used to approximate a suitable shape. To enable test users to experience a product close to series production in the early phases of product development, the use of 3D printing techniques becomes sensible. Once this state is reached, it is necessary to evaluate the usability of the prototype.

Skizze und Prototyp eines Handgriffs in der Bedienung

Fundamentals of usability evaluation

According to the DIN EN ISO 9241 standard series, usability (Engl. Usability) is the extent to which a product can be used by specific users in a specific usage context to achieve specific goals effectively, efficiently, and satisfactorily. Thus, effectiveness, efficiency, and user satisfaction are quantifiable metrics of usability that can be collected during the operation of the tool, i.e., during interaction with it. Evaluation methods are available for collecting these measurement parameters.

Usability evaluation methods can be divided into inspection and test methods according to Nielsen. Inspection methods are conducted by usability professionals and mostly involve checking compliance with heuristics or design guidelines. Here, an experienced usability expert analyzes the human-work tool interface of the technical product for conformity or deviation from existing and recognized guidelines. For hand-operated tools, this usually includes geometric specifications such as grip diameter or grip materials, as well as application-appropriate grip orientations and courses. In addition, the societal compatibilities recognized in the respective cultural circle and the affordance, the so-called offer character, of the design must be checked. For example, in the Western cultural circle, the green design of a control element is usually associated with the start of a process, while a red color marks the end of a process. The same applies to widespread symbols and icons, which should be considered accordingly in the design.

In contrast to these analytical methods, the second group of methods, the test methods, involves an empirical approach. It is necessary to enter the usage context and conduct observations and interviews with real users. The gold standard test method is the Usability Test, an evaluation of usability with users based on defined task processing, usually through participant observation.

Reale Nutzer bedienen die Geräte in realer Nutzungsumgebung

Do you want to develop future-oriented and innovative work tools and devices and are looking for a reliable partner? Our experts in user-centered technology development and design are ready to assist you in this challenge.


Human-Centered-Design, a Corporate Philosophy

Understanding the intrinsic value of the Human-Centered-Design maturity

The term “user-centered design” traditionally refers to the development of interactive systems, such as physical products like machine tools or digital services like cloud-based management dashboards, with a focus on the actual user. In the endeavor to further optimize these interactive systems, the human-centered approach has long been of relevance not only in selected phases of development.
Looking at the guiding principles of global players, one can recognize the penetration of the HCD approach (Human-Centered Design) down to the lowest levels.

This not only brings advantages for the later users in our modern work world through a positive user experience and effective, efficient, and satisfying interaction with these systems. The more deeply the “human-centered” approach is embedded in companies (so-called HCD maturity), the more stakeholders are influenced by it. Thus, it would be wrong to consider such a level of maturity merely as an effort. Instead, it represents a source of sustainable and socially responsible innovative strength. This can be used to create superior products and services as well as a more desirable work environment.


„HCD affects industries such as medical technology, not only impacting the professionals who often represent the primary users. Developers and product owners feel that their individual strengths and personality are valued and utilized, and that they can engage in responsible and meaningful work. Patients feel secure and acknowledged through this focus on health, safety, and well-being in dealing with human-centered interactive systems.“


But where should one start? In the daily work jungle, such approaches may seem more ideological in nature, or aren’t they?

Often, it helps to first gain clarity about the associated activities through a clear and holistic structure to be able to tackle the first steps purposefully. The ISO 9241-220 provides the corresponding framework in the form of the holistically oriented HCD process model. In this model, HCD activities of various process categories (levels) are structured in the context of internal company processes and hierarchies. These range from everyday, operational work in and around projects to organizational and structural processes up to the overarching corporate strategy. Within these categories, numerous sub-processes can be carried out to improve the overall HCD maturity level. While at the highest level, guiding principles and corporate policies need to be aligned with human-centered design to sustainably increase the HCD maturity level, only the individual necessary actions in the daily development routine of experts in their respective fields lead to an initiative (introduction of HCD processes) and constant (operation of HCD processes) advancement of the HCD processes.

Prozess modell
Based on ISO 9241-220:2019-03

Central to this is the human-centered quality, which can extend across all areas, from specific product interface quality to the work quality of development teams. Potential HCD processes must first be identified, which are possible at all levels of the HCD process model.


„HCD processes must first be planned and managed and brought into the right usage context. Subsequently, the requirements are specified, which are to be shaped through human-centered design. These must then be evaluated by the decisive and representative users using appropriate metrics within the respective HCD process.“

To iteratively improve these in the respective areas, it is therefore essential for all participants to understand and comprehend the following aspects: the purpose of an HCD process, such as tapping into new customer segments through information about new usage contexts and user needs – the associated benefits, such as claiming more market shares through knowledge of the necessary usage requirements and relevant acceptance criteria and the ability to effectively utilize them in development – the translation into outcomes, such as faster and more comfortable operation in the respective work task, which can lead to the consolidation of an innovative and forward-looking company image – through human-centered activities, such as continuous usage context analysis in the respective product development process, which is to be carried out sustainably and socially responsibly.

Responsible handling of such HCD processes always involves a constant assessment of the associated potential opportunities as well as expenditures and risks in the context of developing interactive systems. Achieving a “human-centered design” maturity level thus represents not a sprint, but a marathon, in which, however, every step in the right direction pays off.

Contributions in this topic field

Standards & References