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2.3 The fabrication process for a MEMS Pirani sensor

This section is fairly long, but is best read in one go. If you run out of time, reschedule your study to allow you to start again from here.

Thin layers of material are added to the surface by a variety of means, depending on the material to be deposited, and what is already on the wafer.

The sensor starts off, as so many microsensors do, with a silicon wafer, shown in cross section in Author(s): The Open University

7.2 The professional engineer

It has been suggested that there are four main criteria that identify a profession:

Custody of a clearly definable and valuable body of knowledge and understanding associated with a long period of training.

A strong unitary organization which ensures that the profession generally speaks with ‘one voice’.

Clearly defined and rigorous entry standards, backed up by a requirement to register with the profes
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7.1 The engineer and society

Section 2 outlined some of the needs for engineering. Society relies on engineers to create solutions to the problems involved in meeting those needs.

This is a good time to pause and point out that inevitably, in return for all this fun and power, engineers have a responsibility to society. The people who employ our services, directly or indirectly, have to have an assurance that we are working within certain social, safety and ethical boundaries. Particularly given the increasing tren
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Learning outcomes

By the end of this unit you should be able to:

  • critically evaluate disasters and their causes, especially from mechanical or material failures;

  • demonstrate the importance of systematic and rigorous analysis of disasters, so that future failures can be avoided or prevented.


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3.3 Magnetic tape recorders

Experiments showed that the use of paper tape coated with iron oxide particles significantly improved the signal-to-noise ratio and enabled a lower tape speed to be used. A plastic-based version of this magnetic tape, developed by the German company BASF, led to the development of a commercial tape recorder with audio characteristics that could nearly match those of the gramophone record, but not at an economical price. Secret work on tape recorders was undertaken by the Germans throug
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3.1 Introduction

I've an opera here you shan't escape – on miles and miles of recording tape.

Flanders, M. and Swann, D. (1977) ‘The Song of Reproduction’ from The Songs of Michael Flanders and Donald Swann, London, Elm Tree Books and St George's Press, p. 99

Sounds, pictures, measurement data, financial statistics, personal details, etc. can all be recorded and stored on magnetic media, i.e. m
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2.3 Berliner experiments with plates

Emile Berliner was a young German immigrant to the USA with an interest in science. Whilst working in several menial jobs he educated himself in basic physics and chemistry, eventually building a small laboratory at his boarding house. Experiments with electricity and acoustics led to his invention of a new telephone transmitter, which he sold, enabling him to set up as a full-time inventor. He became interested in recording sound through studying a device called the phonoautograph. This appa
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1 Biological materials

Materials engineers have long recognised the impressive range and combination of properties offered by biological materials. Figure 1 shows some representative examples of the combination of tensile strength and toughness (measured by Young's modulus, or elastic modulus for polymers) offered by natural mat
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Introduction

This unit examines how self-assembled structures based on lipids and proteins provide a framework for cellular processes.

This unit is an adapted extract from the Open University course Engineering small worlds: micro and nano technologies (T356).


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Acknowledgements

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

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5.2 Cancellation and reinforcement

I have shown that a phase difference between two points in space arises as a natural consequence of the finite time it takes a pressure wave to travel between two points in space. This is not the only way in which a phase difference can arise. A phase difference can arise between two sine waves if one is delayed relative to the other. Also, almost any form of electronic sound-processing equipment affects the phase of the signal it is processing, so that what comes out is not in phase with wha
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5.4 Methodology, method, technique, and tools

As you engage with systems thinking and practice you will become aware how different authors refer to systems methodologies, methods, techniques, and tools, as well as systems approaches. Having just spent some time explaining what I mean by a systems approach, I now want to distinguish between methodology, method, technique and tool.

Several authors and practitioners have emphasised the significance of the term methodologies rather than methods in relation to Systems. A method i
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1.1 Making sense of the metaphor

The metaphor of the juggler keeping the four balls in the air is a powerful way for me to think about what I do when I try to be effective in my practice. It matches with my experience: it takes concentration and skill to do it well. But metaphors conceal features of experience, as well as calling them to attention. The juggler metaphor conceals that the four elements of effective practice often seem to be related. I cannot juggle them as if they were independent of each other. I can imagine
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9.9 Perspectives review

Just as you were completing your rich picture, I asked you to identify and record any stakeholdings, thinking, feelings, and views about what to do. In the next activity, I invite you to do a similar exercise based on where you are now. I then want you to re-examine the notes and compare the earlier perspective against your current perspective.

Expect to spend about half an hour on this activity.

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2.5 Review

The title of this unit could have been Juggling with complexity: searching for system. This title seemed to capture something essential about the unit. Juggling is a rich metaphor and will be used explicitly in Part 3. But it also carries the idea of a skill that needs to be practised and that might seem incredibly awkward to begin with. You may find this idea helpful as you review your work in Part 1. Juggling is also a skill that, once practised, becomes second nature. This too may b
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2.3 Taking responsibility for your own learning

Not much of this unit conforms to the traditional pattern I mentioned earlier – the theory-example-exercise pattern. In particular, you will find you are expected to discover much of it for yourself. Why is this? This is a legitimate question and deserves a full answer. One year, a student at a residential summer school complained I had not taught him properly. I was, he told me, an expert and so why did I not demonstrate how to tackle the problem he was working on and pass my expertise on
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3.2 Learning by experience

It's a familiar idea but it implies two activities: learning and experiencing. Both activities need to happen if I am to say that learning from experience has happened. Experiencing seems to have two components. The first is the quality of attention that allows me to notice the experience and its components. The second is memory. Calling experience to mind allows me to examine the experience and to think about it in ways that were not possible at the time. Learning is what I take away from th
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3.1 What are you hoping to learn?

Anticipations and preconceptions are an important determinant of how people learn, so before you read on, I would like to you to record some of what you are experiencing now as you begin the course.

It's important to get these impressions noted down now, because new ideas and new impressions will quickly overlay the experience. What you are experiencing now will be re-interpreted as new understandings emerge. You are also likely to form some judgements about your expectations. So before
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2 Part 1 Starting the unit

Welcome to T306_2 Managing complexity: a systems approach – introduction. As I write, I experience a sense of excitement. For me, as for you, this is the beginning of the unit. These are the first few sentences I'm writing and so, although I have a good idea of how the unit is going to turn out, the details are by no means clear. Nevertheless, the excitement and anticipation I, and maybe you, are experiencing now is an important ingredient in what will become our experiences of the u
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7 Ergonomics and human factors

This section discusses designing for human capabilities and limitations. It introduces the study of ergonomics which can offer general guidelines as well as specific suggestions for good, user-centred product design.

Taking the user as the central point of reference for the design and evaluation of products is the approach encouraged by ergonomists.

The field of ergonomics (also known as human factors engineering) is the systematic study of human capabilities, limitations and requ
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