1. Microrobotics for MEMs and Nanotechnologies
Microrobotic Components:
1.) Sensors
2.) Actuators introduction, examples (SPM)
3.) Bearing & Guidance System
“Guidages”, “Führungen”
4) Control! Integral part of 1-3)
Hannes Bleuler
EPFL, LSRO Laboratoire de Systèmes Robotiques

2. In Microrobotics, these components are very much integrated!

3. Sensors: Classification criteria
What is measured? (distance, force, pressure, T, t, frequ., light, field, chemical composition …)

4. Sensors: Classification criteria
what
Physical Principle (Optical, acoustical, electrostatic, magnetic, hall, inductive, eddy currents, dilatation, piezoelectric, piezoresistive, magnetnetoresistive…)

5. Sensors: Classification criteria
what
Physical principle
Metrological principles: absolute, relative, incremental, averaging, local, intensity, time of flight, phase, Indirect meast.: nulling.

6. Sensors: Classification criteria
what
Physical principle
Metrology
Technology (Analog, discrete, integrated (MEMS), thick-film, Screen Printing, electronics (CMOS,CCD,SMD…)

7. standard Printed Circuit board
Example: Technology choice (PCB) leads to new sensor: Transverse Flux Sensor
excitation coil
pickup coil
standard Printed Circuit board
Analog
RF Electromagnetic
Distance, conductivity
PCB technology
Philippe Bühler,
ISMB 9, Aug. 2004

8. Transverse Flux Sensor
Excitation frequ.
20 kHz to 3 MHz
depending on electr.
& magnetic properties
of target material
Potential for high precision since there is
averaging over large target area.
Unaffected by low frequ. & static fields.

9. Simple structure: Easy to adapt to harsh environements (hot, UHV, corrosive, liquid)
Little effect of temperature: Has been made for T up to 500 °C
UHV compatibility! In these cases not PCB, but screen printing on Alumine substrate, Ag–Pd conductors

10. for Local
Measurements
Other example

11. Just like an actuator, a sensor is basically a transducer from one form of energy to another
Disturbances
Input power
e.g. mechanical
Output power
e.g. electrical
Losses

12. Piezoelectric transducers:
Piezo as an actuator:
charge –> strain –> stress
Piezo as a sensor:
stress –> strain –> charge

13. Piezoelectric materials
quartz (weak)
salt (very weak)
polycrystaline ferroelectric ceramics:
BaTiO3,
Lead Zirconate Titanate (PZT)

14. Basic mechanism: Stress –> strain –> charge
Also charge –> strain (actuator)
complex geometry (polarisation direction, strain tensor, shear…)
small displacements, high forces, high voltages (µm to tens of µm for cm size PZT, 100s of Volt)
nonlinearity, hysteresis
Ceramics –> brittle –> prestress