[robotics-worldwide] [jobs] Open PhD thesis position in microbotics

Cédric CLEVY cclevy at femto-st.fr
Wed Apr 29 12:06:15 PDT 2015

PhD Thesis title:
 Manipulation and 3D Robotized Micro-assembly of Nano-lamellas based
nanophotonic structures in SEM environment


Context of the PhD Thesis:

The proposed work falls within the general context of micro-assembly
(assembly of components with dimensions generally smaller than 100 µm) and
will be applied to the realization of innovative nanophotonic functions and
devices. Many scientific and technological challenges remain in these fields
where both AS2M and Optical departments of FEMTO-ST Institute have
world-class expertise.

In the field of robotic micro-assembly, many results dealing with design,
realization and control of different kinds of micromechatronic systems have
been obtained. Several micro-assembly platforms have also been developed.
Achieved studies enable to assemble components of few tens of micrometers in
teleoperated or automated modes based on powerful vision or force feedback
(Fig. 1). Micro-assembling face several specificities such as the
predominance of surface forces over volume forces which induce complex
behaviors (sticking like effects, difficulties to release accurately a
component…), the very small free space (induces strong limitations in terms
of actuators size, number of actuators or sensors in the area of interest),
the use of actuators with highly non-linear behaviors, very bad signal to
noise ratio….

In the field of nanophotonics, several theoretical works and related
experimental validations improved a lot the understanding of physical
effects induced by light transmission through metallic lamellas including
sub-wavelength size holes. Recent progresses of clean room microfabrication
processes combined with these theoretical works conduct to innovative
optical functionalities which directly open to the use of new optical
phenomena at this scale (Fig 1-d).
Fig1: (a) Example of optical microsystem through robotic micro-assembly
approach (b) Micro-assembly platform comprising 9 Degrees of Freedom (DoF),
a smart microgripper, 3 high magnification cameras and a laser sensor (c)
Example of optical components being manipulated by a microgripper (size
roughly 100 times bigger that the ones studied in the proposed PhD thesis)
(d-top) Bragg grating with giant form factor obtained by ridge sidewall
machining (d-bottom) lamella structured with studs.

PhD thesis objectives:

Manipulating and micro-assembly of lamellas on nanophotonic structures
targets very promising and first order scientific challenges. It is notably
required to define a gripping strategy, to develop adequate gripping tools
(including force sensing) and to define a strategy for accurate assembly
including bonding aspects all inside of a Scanning Electron Microscope

The manipulation of such a lamella is a complex problem that thesis works
has to be addressed. Particular attention will be paid to the gripping tasks
due to the high fragility of these components (form factor higher than 20),
their very small size (largest dimension of few tens of micrometers order)
and the need to ensure their position relative to the grippers frame very
accurately. Works will notably include the design of gripping tools and the
definition of associated gripping strategies to ensure the high quality
assembly despite many specificities due to the scale (difficulties to
integrate sensors, actuators with non-linear behaviors, varying behaviors
inducing varying models parameters, surface force influence…).
Once a lamella is gripped, its trajectory has to be accurately controlled
during the whole assembly process to successfully place it on the optical
structure with planar contact. This step is particularly critical because it
notably requires controlling all the rotations of the lamella, error angles
directly and strongly reducing the optical performances of the assembled
photonic structure. To tackle this difficulty, the control of the robotic
micro-assembly platform (including the microgripper with force sensing
capabilities) may be done by using an active based feedback (using optical
performances measurement of the photonic component during its assembly in
real time). Such an approach requires a multiphysic (mechanics-optics) model
correlating the position of the lamella with the optical performances of the
whole photonic structure.

The PhD student will manage the milestones including experimental
validations that will be done in air environment at first. Experiments will
gradually converge towards the integration of main results to the vacuum
environment of a SEM. The final objective of the PhD will be to achieve the
structuration, assembly and bonding of a photonic structure through robotic
micro-assembly approach inside a SEM chamber. SEM environment presents many
interests but reversely brings strong constraints (very low volume,
limitations in terms of materials to be used, specific experimentation
protocols, specific physical behaviors).

In terms of applications, several of them are already identified and have a
promising industrial potential. These applications may be used as case study
during the PhD thesis (based on waveguides or multi-layered optical
structures). Due to these facts, patents may be expected in addition to high
level journals that are targeted for scientific contributions.

Role of the PhD student in the whole project:

The PhD student will be jointly advised by AS2M (Philippe Lutz and Cédric
Clévy) and MN2S (Nadège Courjal) departments of FEMTO-ST Institute and then
will take benefits of the expertise of both teams in their respective
fields. The PhD student will then directly contribute to the collaboration
between these departments. He/She will also take benefit from the µ-robotex 
platform (which includes an innovative powerful SEM equipped with FIB,
microrobotic tools inside of the chamber…) and from the expertise of
research staff dedicated to this platform. The PhD student may also use
another nano-robotic platform working in air environment and will take part
of the design step of photonic lamellas. Reversely, progresses achieved by
the PhD student will bring new ideas, new scientific exchanges as well as in
fields of robotics, optics and microscopy.

Advisory team of the PhD: 

Cédric Clévy  (Associate professor – CODE team, AS2M department , FEMTO-ST
Philippe Lutz (Full professor and advisor of the PhD– CODE team, AS2M
department, FEMTO-ST Institute)
Nadège Courjal (Associate Professor-HDR – Optics department, FEMTO-ST

Requested skills:

Profiles based on/or merging competencies of mechatronics, robotics,
automatic control and/or instrumentation will be considered with a great
attention. The proposed thesis is for curious, inventive, dynamic
appliquants having a strong scientific background and a sense of
collaborative works. Experience of research and experimentation will be
appreciated extra points.


3 years duration doctoral contract, The PhD thesis beginning is expected in
October 2015.

Application before may 20, 2015:

Please send your application documents to Cédric Clévy (cclevy at femto-st.fr)
including a detailed CV and a motivation letter dedicated to the proposed
position. You may add additional documents such as the marks and ranks you
obtained during your master degree or engineering school. 

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