Microrobotics for Micromanipulation

Nicolas Chaillet, Stephane Regnier

• Publisher: Wiley-ISTE
• Year: 2013
• ISBN:
  9781118622384
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Robotics
• Index: Technology & Engineering

Microrobotics is an emerging and booming area with many and various applications, including in fields such as industrial/manufacturing robotics, medical robotics, and laboratory instrumentation.

Microrobotics for Micromanipulation presents for the first time, in detail, a treatment of the field of robotics dedicated to handling objects of micrometer dimensions. At these dimensions, the behavior of objects is significantly different from the better known, larger scales, which leads to implementation techniques that can be radically different from the more commonly used solutions.

This book details the behaviors of objects at the micrometer scale and provides robotics solutions that are suitable, in terms of actuators, grippers, manipulators, environmental perception, and microtechnology. Worked examples are included in the book - enabling engineers, students and researchers to familiarize themselves with this emerging area and to contribute to its development.

Chapter 1

The Physics of the Microworld 1

1.1. Introduction

The term “Micromanipulation” refers to the range of techniques available for the manipulation of objects with sizes ranging from 1 mm to 1 µm. The range in which micromanipulation operates is commonly referred to as the microworld.1 This is in contrast to the “macroworld”, which consists of those objects whose size is greater than 1 mm. The workings of this world cannot easily be described using analogies with existing systems in the macroworld, but require a separate description all of their own.

1.1.1. Scale effect

Miniaturization of an object or process can prove complex, because the range of physical phenomena involved may not all change in the same manner as the scale is reduced. If, for example, we were to scale down a guitar, we would obtain a new guitar whose range of notes had become much higher. The resonant frequencies of the strings increase as their dimensions are reduced. In order to obtain a miniaturized guitar with the same range of notes as a conventional guitar, we would need to completely redesign the instrument. The same is true for most behaviors of a system – they will change as the scale is reduced. The impact of the scale change on physical phenomena is commonly known as the “scale effect”.

The physical phenomena which dominate on a human scale, such as weight or inertia, are mostly volumic. In other words, they are directly proportional to the volume of the object under consideration. Thus, if we change between a cube of steel with sides whose lengths l are one centimeter and a cube with sides whose lengths are

(ten times smaller), the characteristic dimension l has been reduced by a factor of 10, whereas its mass changes from 7.9 grams to 7.9 milligrams and so has been reduced by a factor of

.

Certain physical phenomena, generally ones that are less familiar in everyday life, are not volumic. An example of this is the surface tension force. This is a length-based effect, and so its evolution is proportional to the scale under consideration. Hence the surface tension of a cube with sides of length l is directly proportional to this length. For a cube ten times smaller, with length l′, the surface tension force is also simply divided by

. Consequently, this effect decreases in strength much less rapidly during the miniaturization process. The miniaturization of a concept is subject to the scale effect, which modifies the relative strength of one physical effect compared to another. This modification could either render the miniaturized device inoperable or improve its performance.

1.1.2. Illustration of the scale effect

The scale effect can be illustrated in everyday terms by comparing the methods of locomotion and behavior of insects and people as a result of their significant differences in size.

A first insight into the impact of the scale effect can be drawn from observing aquatic insects walking along the surface of a pond. The insects travel on top of the surface without any part of themselves being immersed in the water. They use the surface tension between the liquid surface and the hydrophobic tips of their legs. On the human scale, travel within water is governed by the equilibrium between the Archimedes force and the weight, which requires a significant volume to be immersed in order to be in equilibrium. The scale effect is volumic for the Archimedes force and for weight, whereas it is length-based for surface tension. Consequently, the latter rapidly becomes dominant over the two other effects during the miniaturization process. On the scale of an insect, the use of surface tension to travel across a liquid medium is therefore more effective ...

Table of contents

• Cover
• Title Page
• Copyright
• Foreword
• Introduction
• Chapter 1: The Physics of the Microworld
• Chapter 2: Actuators for Microrobotics
• Chapter 3: Microhandling and Micromanipulation Strategies
• Chapter 4: Architecture of a Micromanipulation Station
• Chapter 5: Microtechnologies and Micromanipulation
• Chapter 6: Future Prospects
• Chapter 7: Solutions to Exercises
• Bibliography
• List of Authors
• Index