Medical device product design and control of man-machine interface

Although improper medical apparatus product design does not always and medical apparatus product related errors. On the user's research has shown that the lack of adequate training for such failures of 70 per cent to 90 per cent. But even those who may have been the "punishment", or other harm to the patient, one of which is the wrong man-machine interface design many loss exposures are hidden in conventional medical work and medical apparatus product use, to the knowledge of physicians and patients bring disaster. Medical device and the user is directly related to the medical devices for human-machine interface. The pros and cons of man-machine interface based sauce to medical equipment, reliable and patient safety.

1, the meaning of human-machine interface

Man product interface, called "man-machine interface".

Man-machine interface between user and product systems, is passed between people and products, exchange of information by the media. Product interface exists in people — from information exchanges, and even can be said that as long as there are people in the area of information exchange between all belong to the design of the interface, its wide meaning elements, reflects the relationship between the characters.

Man-machine interface design theory of development of the organic integration of the various related subjects, and constantly improve their own theory of basic concepts, theoretical systems as well as research methods, the study and application scope is very wide range of integrated edge disciplines.

HMI studies including computer technology, psychology, ergonomics, design arts, sociology and anthropology, and other aspects related to the computer, industrial design, new media, psychology, sociology and anthropology, and other disciplines.

Man-machine interface are used, ready to use (such as a school team, setting and open), or the maintenance to keep (such as repair, cleaning), all of the instruments and the relationship between components.

It includes control instruments work such as switches, buttons and knobs and other hardware, including LEDs, video, audio and Visual alerts and other, also includes a series of logic, their guidance system how to respond to the user's instructions, including how, when, and how the information in the form of feedback to the user. An important aspect of human-machine interface is what logic information display and control behavior and user capacity, expectations, the most likely behavior.

2. Human-machine interface design of medical devices

2.1 medical device control/display unit arrangement and design

Many of the medical device is a great console, a row of control keys and display devices.

Designers should consider the user's ability to quickly and effectively identify control, power and display key; contact and precise setting and control; accurate read display information; the control and the associated display. Achieve satisfactory stroke include effective control and display functions, clear and unambiguous identification, very easy to operate the press. Clear instructions and effective alarm is also very important. But unfortunately, in the control and display unit design above, there are many examples of the error. The following design errors are present in a particular brand of anesthesia machine design.

As Figure 1, the anesthesia machine in the oxygen pipe mouth of a rotating switch below, every minute can give fresh air flow increase 5L oxygen.

It is an emergency or power failure during rapid oxygenation. Extra oxygen flow but does not appear on the electronic flowmeter. Accidentally touches this switch will cause mild anaesthetic, so it should be more tips for visible, for example, in the display screen on the display.

\\ Figure 1

As Figure 2, the anesthesia machine has 3 main knob is used to set the mode of ventilators.

Set is from the control panel to the right to move to the left, do not meet the user's habits. Because most of us reading view is down to the right of action, as we read a book.

Figure 2

This example illustrates the fact that some looks very small design mistakes can lead to very serious problems.

For medical apparatus developed by elements of the guidelines to reduce the incidence of such problems. The following is medical apparatus design interface design guidelines.

As far as possible to ensure that all aspects of the design and the user's expectations have been.

Taking into account the user's previous habits and the use of established habits. In the design of the platform, control and display section, to make them consistent with the user's ability. These capabilities include manual, sensitivity, memory, vision and hearing. Organize better control and display the part of the arrangement, and to ensure the relevance of the control and display. These facilities may be appropriate to reduce the burden on the user's memory. Determine the auditory signal strength, so that they can be very easy to use user hear medical apparatus. And consider the role of environmental noise. Ensure visual signal strength is sufficient to enable users in a variety of environmental light exposure can be received. Similarly, light intensity and color distinction can help optimize recognition degree. Ensure that identifies and displays at certain angles and distances can be easily seen. Label size, contrast, color and depth of the display must be carefully considered. Ensure that the abbreviations, labels, text, and acronyms are marked or display, but also to the use of medical devices and user manual for instructions. If possible, they should be and standard terminology. Design of control switches and knobs should and user base is consistent with customary (depending on the user's learning and existing standards for medical devices).

2.2 therapy machine software design

Drinking more control and display unit, users must identify and consolidate a lot of independent information.

Now the trend is for software to add more features, so you can reduce the control and display the number of parts, but this is also another way to increase the user load. As shown in Figure 3, in a small display screen, there are too many input information. Although there are on the PanelLittle control and display unit, but a large amount of information displayed on the user's memory make high demands. Large amounts of information must be sequentially in memory, so it might hamper the user at the same time observe the other related data. If you lack sufficient hints and directions maps, users will begin to be lost in the information system. Similarly, if there is no accurate functional status feedback and tips, user may misconceptions about the display of the data or make incorrect responses.

Figure 3

Caused by the software design and many use the errors have been attributed to the other relevant factors, and because of these errors in analysis and correction is hard to think clearly and be found.

Similarly, software-related errors are subtle. For example, because of the inconvenience of data entry steps result in user frustration, and users have made some mistakes, although these errors are not directly represented by these bad input steps. Do not clear the command structure and menus of acronyms or abbreviations can also cause serious error. To overcome this problem is also related to the design criteria, as follows:

In the title, default, icons, and tables to use and designed to maintain consistency, overcome the ambiguities.

Make sure the user instantly know what state the current use of medical devices. In the user operation is to provide timely and clear feedback. User prompts, menus, and other information should prompt the user to consider the most important step, instead of making users "deadlock". The error occurs, provide the user with sufficient resources to provide clear guidelines for the correct and repair. Do not provide no format, intensive or too brief information, because it will confuse users and their burden. Use can be acceptable symbols, icons, colors, and the default for the effective, economical and fast delivery information. Simple hardware solution can use, not overly dependent on software, for example, using a button you can achieve timely and effective functionality. As a highly important information ad hoc separate display section. In this case, do not appear in these sections to other data.

2.3 parts Assembly design of medical devices

Figure 4

Now there are many different manufacturers are producing the same medical device part.

You can see in the market to different types of wire, pipe, interfaces, and valves. Different types of parts are often looks looks very similar, but it is difficult to cater, caused by bad or incorrect installation. Figure 4 illustrates because similar port, users will know what to do, a connection to the same result in errors. In fact, these accidents are often able to design to prevent them from occurring. When conducting user research, testing, and simulation, medical device components and accessory parts should be treated as part of the system instead of separate elements, this point is critical. Related design guidelines are as follows:

Wires, pipes, connectors, valves and other hardware should be very easy to install and connect.

If you go through proper design, improper installation should be impossible or very difficult, or it can be easily found and corrected. User notes should be easy to understand, the warning should be obvious. If a dangerous cannot rely on the design, color and other labels should help the user correctly connected components or the installation part. Circuit contact part should be protection (such as conductor insulation package), because there may cause leakage, short circuit, etc. Components and parts should be numbered so that the broken parts you can rapidly be replaced.

Design of medical devices of alarm 2.4

Alarm and warning is to alert the user that the patient status and medical device itself, this seemingly straightforward features are often complex.

In many circumstances, the alert is at the same time or intermittently from one or more of the medical device, to identify in their difficult medical staff can easily distracted, the alert may be treated as a nuisance or a part of the background. They are also often able to bring pressure to the user. Environmental noise and numerous Visual display information often hide away specific sounds and acoustic signals, too much sound alerts can hide away other alerts. Due to the effects of electromagnetic interference, static or alert over sensitive often caused error alerts. So test the various environmental trigger alerts is very important. In the alert design has the following design principles:

In the design and test alert, consider using the environment and other medical devices used.

Ensure that the audio and Visual alarms and other important alerts contain the design requirements. Carefully considered overly sensitive, electromagnetic interference and other static effect on alert. The alert is to meet or exceed the average user of Visual and auditory range. Make sure the contrast and brightness of the alert color contrast enough in different lighting conditions are detected. Use the encoding (such as color) to the corresponding user established habits. Ensure that the design of the alert are different, if possible, and the other at the same time use the alerts on medical devices. Enable alerts on critical issues in a timely manner is triggered when they occur. By alerts can identify the source of the problem, this is important. Consider giving important alerts to priority level. Important alert should have more audiovisual signals. To set alert, you can let them temporarily muted. The alert should have Visual cues, cue status and mechanisms to identify the cause of the alarm.

3. other elements of the medical device interface

3.1 scale, intensity and angle

And medical devices contact work platform, seat and console should be appropriate for the user group.

Human dimension data is very important for the design of medical devices, the control should be available and range, the seat should be very comfortable. The body dimension data is widely used in anesthesia workstation, Dentists Workbench and other medical device design, these data can also be used for many families, medical device, such as wheelchairs. In total these design, compact, compact and concise structure is very important. For clinical and home environment awareness is also very important.

Important but very difficult to understand is the tool of biomechanical problems, these tools include a hammer, dental instruments and apparatus, control handle, keyboards and other needs of the actual sensitivity or intensity repeated movement of equipment/.

As shown in Figure 5 of a kind commonly used medical equipment, scaling, strength requirement is very high. A sound and dental surgery is often required in the limited space in the use of instruments, problems might not only and the intensity of the sensitivity, but also and visibility, visibility and other instruments used in conjunction with degrees.

Figure 5

Change the way you use 3.2

Designers are often encouraged to design a unique and distinctive products.

But this Winery to medical units of the user from using and training impact because doctors and nurses have become accustomed to the original instruments use a specific pattern. For example, when the two models seem to look very similar, but it requires two different uses for this original set up on one of the medical device in use accustomed to will and another phase of the conflict. This will likely be similar to the operation of the product. For example, are two very similar medical device ON/OFF on the switch position swap, user actions from a medical device to another medical equipment operation, often unconsciously repeating the original rotary switch. Similar problems often occur in medical device design or renovation and design process. Such discussions are not encourage innovation and promote designers should carefully assess the change user to use the methods on the interface.

4. concluding remarks

Discusses the many medical device design mistakes is to stress the importance of using design guidelines.

Good medical device interface design can reduce the use of related incidents, increase the plasticity of the medical device products. But now the market of medical equipment is very little human-machine interface design is considered very well, and this requires the various elements of the interface design to comply with the general breakdown of the various design guidelines to reduce medical accidents.