SIGNAL SOURCES FOR SIMULATION, TESTING, AND CALIBRATION - Design and Development of Medical Electronic Instrumentation - page 295

One Teledeltos Square

∂ Jy
∂ y

[

δ y

]

δ x

Jy +

δ x

δ y

Jx δ y

∂ Jx
∂ x

[ ]

Jx + δ x δ y

Jy δ x

Teledeltos Torso cut-out

DC
Supply

High Input
Impedance
DVM

V to I Converter

Pin holed region

Carbon Paper

Graph Paper

Figure 6.32 Teledeltos paper is a resistive paper that has uniform resistance. It can be cut to the scaled shape of the body region to be inves-
tigated. Electrodes painted with conductive ink allow connection to current-voltage sources. Inhomogeneities are introduced by means of
perforations or silver spots (e.g., pinhole region simulating lungs). Field intensity values are read with sharp-tipped voltmeter probes. A sheet
of carbon copy paper and graph paper make it easy to trace equipotential lines and gradients.

ow
is essentially in two dimensions (i.e., across the surface of the paper but not through its
thickness from one face to the other). Suppose that the vector J (A/m) represents the cur-
rent density per unit width at some point on the Teledeltos sheet. Then the electric

Consider how Teledeltos can be used to solve electrical fi field problems. The current fl

fi field (or

voltage gradient) at the same point in the sheet is

E J ρ (V/m)

where ρ is the speci fi c resistance of the sheet. Teledeltos paper has a uniform grid printed

on it, and ρ represents the resistance between opposite sides of a grid square.