IX) Telemetry

Question 1

What are the main component for a wireless system ?

Answer 1

External controler on the skin and the implanted device connected to neural interfaces

Question 2

What are the two requirements for wireless systems ?

Answer 2

Shall deliver energy supply for the iplant electronics for recording or stimulation
Shall transmit data to and from the implant

Question 3

What are the objective surrounding the creation of a wireless system ?

Answer 3

Create a magnetic field, transmit and receiveenergy via this magnetic field

Question 4

What are the laws of maxwell ?

Answer 4

a complete description of electrical and magnetic fields and current flow.

Question 5

What is “B”

Answer 5

the magnetic induction, it is when the current flow (I) through a straight conductor leads to magnetic induction (B) in dependance of a certain distance.

Question 6

What is the role of the coil in magnetic induction ?

Answer 6

It is an helical wound conductor. It creates an homogeneous fild that is dependent on density of turns (n) and current (I)

Question 7

how to calcul the density of turns (n)

Answer 7

n= N/d

N is the number of turns and D the lentght of coil.

Question 8

What is given as a relation of the magnetic field (H) ad the magnetic induction (B) ?

Answer 8

it is “mu”, or pemeability : B= mu x H

Question 9

How does magnetic field is calculated ?

Answer 9

it is calculated for a current flow through a straight conductor (H= I / (2 x pi x a))

Question 10

What is defined as a short coil ?

Answer 10

A coil that the thickness is much smaller than its radius

Question 11

What is the magnetic flux ?

Answer 11

It is a measure that tells how many magnetic field lines (Bs) cross a given area A.

magneticflux = BxA

It is taken to visualize how field lines cross the space between two transmission coils.

Question 12

What is the magnetic potential ?

Answer 12

it is for linear conductive loops. It sums up the magnetic flux of N loops ithin a coil of an area A

(= N x mu x H x A)

Question 13

What is the idea behind the faraday’s law of induction ?

Answer 13

If Magnetic field change iver time, it changes voltage.

We need a temporally changing current in another conductor to induce the changing magnetic induction.

Question 14

What is the property of a coil ?

Answer 14

It creates inductance

Question 15

What is the inductance ?

Answer 15

It describes a relation between current through conudctor and magnetic flux through a single loop.

L = (NxmuxHxA)/I

Question 16

How to calculate the inductance of a loop ?

Answer 16

L = N(squared) x mu0 x r x ln(D/dLeiter)

D/dLeither &laquo_space;0,001

Question 17

What does the mutual inductance represents ?

Answer 17

It describes the coupling of two electric circuits via a magnetic iels. It is a basic measure for inductive energy and data transmission (how two coils influence eachothers) 221

Question 18

What is the coefficient of coupling ?

Answer 18

The coefficient of coupling k is a qualitative
measure independent from geometric dimensions
• It is a relation between the mutual inductance and
the inductances of the coils in the primary and
secondary circuit
• Inductively coupled systems: k in the % range

Question 19

What is the role of the external coil ?

Answer 19

To induce power and send
data to the implant unit
wirelessly using magnetic
induction

Question 20

What is the role of the internal coil ?

Answer 20

• To collect data and
received power from the
implant unit
• To send data from to
implant to the external coil

Question 21

what is the role of the external part of a resonant circuit ?

Answer 21

• series resonance

- maximize current to drive coil

Question 22

What is a resonant circuit ?

Answer 22

A circuit that consist of a capacitor and an inductor connected together.

Question 23

what is the role of the internal part of a resonant circuit ?

Answer 23

parallel resonance
- maximize voltage to
drive circuit

Question 24

what is the formula to calcul magnetic induction of a coil ?

Answer 24

mu0 x current (I) x density of turn (n)

dencity of turn = number of turns / thrickness of the coil.

Question 25

What is the quality factor ?

Answer 25

It describes the selectivity of a resonant circuit (serial resoniace vs parallalel resonance)

Question 26

Give the calculation ofr hte serial resonance and the one for parallel resonance.

Answer 26

serial : energy stored in conductor on energy turned to heat during 1 period
Q= 1/R(squaredrootofL/C)

parallel : energy stored in capacitor on energy turned to heat during 1 period
R(squarerootofC/L)

Question 27

Where can we find the right frequency to chose ?

Answer 27

International telecommunication union

Question 28

Were to look at the specific absorbtion rate ?

Answer 28

International commission on non ionizing radiation protection (ICNIRP)

Question 29

What the classification of primary coil driver ?

Answer 29

classification of amplifiers and drivers for ertain caracteristics.

Question 30

Describe the D class driver.

Answer 30

Swiching amplifier
two mos fet (transitors)
ideal R is 0 but in reality there is a loss due to switches

Question 31

Describe the E class driver

Answer 31

switching amplifier
1 transitor
ideal source voltage is 0 if FET switches

Question 32

Site the 3 mains type of data codes.

Answer 32

Amplitude shift keying
phase shift keying
frquency shift keying,
load shift keing