electromagnetics at ief - eth zalphard.ethz.ch/hafner/vorles/physicalmod/iefresearch2014.pdf ·...

Institute of Electromagnetic Fields (IEF) Christian Hafner, [email protected] 03.09.2014 1 | |

Christian Hafner, [email protected]

Electromagnetics at IEF


EM Overview

Traditional areas Electrostatics • Capacitors

• High voltage

Magnetostatics • Inductors

• Motors / Generators

Quasistatics • Sensors

• Electronic circuits

• Transmission lines

Electrodynamics • Antennas

• Wave propagation / scattering

• Gratings

• Guided waves

• Resonators...

«Modern areas» • Integrated optics

• Optical computers

• Nearfield optics

• Nano optics

• Photonic crystals

• Metamaterials

• Plasmonics

Mixed with other disciplines

• Semiconductors

• Lasers, LED, LCD

• Solar cells, Photovoltaics

• RF-MEMS

• (Nano-) Robots

• Bio/medical...


Examples of IEF research

• Computational Electromagnetics (software development)

• Numerical Optimization (software development)

• Microwave and mm Wave Technology

• Electromagnetics in Medicine and Biology

• Metamaterials, Photonic Crystals, Plasmonics

• New: Photonic systems (Prof. Leuthold)

• Metamaterials for industrial applications

• Solar cell design

• Near field applications (SNOM, SNMM, TERS...)

• Electron emission / acceleration

• Photonic crystals and EBG structures

• Sensors and sensing


Optimal Design: 2nd harmonic generation

COMSOL simulation

Various optimizers

Triple point problem!

Martin Spieser


Metamaterials for magnetic field shielding

EWZ project

• Strong rules for maximum magnetic fields at 50Hz in Switzerland require additional shielding

• Extreme wavelength offers attractive opportunities (electronic circuits) for the metamaterial design →

tunable, active, NIC, Gyrator,... → «smart» metamaterials

Anisotropic, homogenous,

low μ metamaterial

Anisotropic, inhomogeneous

metamaterial

Experiment:

Homogenous

meta-layer

Improved metamaterial:

passive circuitry

Active circuits :

Heavy, expensive

Shielding performance: Upto 87% shielding

and suppressed undesired enhancement below resonance frequency

Source B Shielded B

Mustafa Boyvat

Meta-atoms for kHz and THz

ranges


Wireless actuation of forces

LC resonators in external field:

Metamaterials and Wireless

Power Transfer

Strong fields close to high Q

resonance Strong forces

Controlling strength and

direction of forces and torques

via external magnetic field

frequency and magnitude

Easy wireless translational and

rotational motion control

Microrobotic Surgery

Coupled LC Resonators

Wireless Magnetic

Micro-Actuators


Radar absorbing metamaterial: optimal design Arya Fallahi et al. IFH

Simulations using MoM + RCWA

Optimization: RHC ++

Goals (same as for solar cells!):

Lower reflection + Higher absorption +

Broader bandwidth + Better angular stability

All goals may be reached simultaneously!

Maybe surprising:

Metallic structures

on top

reduce reflection!


Photonic structures for space applications Reflecting photonic system

(RPS)

Re-entry from

space

Radiative spectra of shock gas

layered media with roughness

Guided mode resonance structures

woodpiles

Porous reflectors

Inverse opals

Collaboration:

NASA, Material sciences

Nikolay Komarevskiy


Advanced solar cell design

• Nanostructuring for

improving efficiency

• Space applications (low

light, low temperature

• Planned cooperation with

Grätzel + Fontcuberta

(EPFL)

Alexander Dorodnyy


Fast chip to chip communication

x y

z

E-field

y

x

cylindrical holes

copper spacers

conical holes

GSG probe

on-chip excitation

0.45 dB insertion loss from chip-to-

waveguide (at 90GHz)

dipole

Replace metallic wires by dielectric EBG waveguides

Excite modes using on chip antennas

Collaboration with Jan Hesselbarth (Stuttgart)

Nemat Dolatsha


Spatial power combining at 140 GHz

Power amplifier

(phase variable)

• High power

• High gain

• Beam forming (1-D scan)

• Active & passive lens

• Very efficient heat-sinking

Alternative:

2-D space scan;

1-D electronically,

1-D frequency scan

Rod antenna

(10-14 dBi gain)

Power

amplifier

(phase

variable

)

Leaky-wave

antenna

(12-17 dBi gain)


Interaction of THz waves and proteins

Electrokinetically Enhanced THz Spectroscopy for Study of Uniformly Oriented Proteins, CB-SEED-13, Stanford Univ.

sensing at sub-THz frequencies. The length of the waveguide corresponds to several wavelengths (e.g., 14! ) at the center frequency of the operating bandwidth, which results in

several resonant peaks in the desired frequency range. It should be noted that the dynamic range and spectral resolution of the complex-domain electrical system (VNA) in DC-THz Lab are 110

dB and better than 10 Hz, respectively, which is far better than conventional optical techniques

for this part of the spectrum.

In order to extract information on the proteins, the obtained signal needs to be decomposed

into its separate contributions. To this end, a calibration approach comparing the pure liquid and

liquid with suspended proteins will be utilized to minimize interference due to background water.

This could be done by either making a differential measurement, or by sequentially measuring

the spectrum of buffer compared to protein suspended in buffer and dynamically subtracting the difference. The network analyzer setup allows for fast pulsed- measurements for this application

(down to 100 ns width).

(a) (b)

Fig. 1 (a) Conceptual schematic of the (sub) THz waveguide resonator applicable to determine the

complex permittivity of liquid samples. (b) A drawing of implementation of microfluidic channel on top

the (sub)THz waveguide. Inset: electric field distribution at the cross section of the waveguide with

strong electric field on top, exhibiting a good potential for material sensing.

(a) (b)

Fig. 2 (a) Measurement (solid) and simulation (dashed) transmission parameter of a prototype of the

resonator operating at 100 GHz. (b) Simulated transmission parameter with (dashed) and without (solid)

the biomaterial sample.

Microfluidic Channel and Protein Alignment: We aim to control the alignment of the proteins by selectively aligning the dipoles in a

single direction using a quasi- static field. This is necessary since our evanescent mode extends

On static

electric

field

Investigation of electrical properties

of proteins oriented in a certain

direction

Applying static electric field:

• Unipolar translation

• Dipolar orientation


EMF‘s in Medical and Biological Research • Numerical and experimental tools

• Design of experimental setups

providing controlled conditions

• Applications in diagnosis, therapy

and safety assessment

• Clinical and in-vitro studies

Various collaborations

Jürg Fröhlich


Smart sensors for smart phones

3D Magnetometer Applet

RF exposimeter Smart phone intensity on Google map

Projects for

EWZ

Armasuisse

...

Jürg Fröhlich

Marco Zahner

electromagnetics at ief - eth zalphard.ethz.ch/hafner/vorles/physicalmod/iefresearch2014.pdf ·...

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