Electrodermal Measurement System And Method
A method of determining the conductance of the skin of a human or animal, the method including the step of: (a) eliminating any equivalent parasitic voltages in the skin by taking multiple different measurements of the conductance utilizing different probe voltage levels, (b) calculating the conductance from the sampled results of the multiple different measurements.
1 . A method of determining the conductance of the skin of a human or animal, the method including the step of:
(a) eliminating any equivalent parasitic voltages in the skin by taking multiple different measurements of the conductance utilizing different probe voltage levels,
(b) calculating the conductance from the sampled results of the multiple different measurements.
2 . The method as claimed in claim 1 wherein the number of different probe voltage levels is two.
3 . A method of measuring conductance of a human or animal body, the method including the steps of:
(a) interconnecting a first circuit to a grounded body, the first circuit including a first known resistance R 1 connected in series with the human body;
(b) applying a first voltage E 1 to the first circuit;
(c) measuring a voltage drop V 1 across the first known resistance;
(d) applying a second voltage E 2 to the first circuit;
(e) measuring a voltage drop V 2 across the first known resistance; and
(f) calculating a conductance S substantially in accordance with the equation:
S
=
(
V
2
-
V
1
)
R
1
(
E
2
-
E
1
)
-
(
V
2
-
V
1
)
.
4 . The method as claimed in claim 3 wherein the steps (a) to (f) are repeated in an iterative manner with the conductance tracked over time.
5 . The method as claimed in claim 4 wherein the repetition rate is greater than 100 Hertz.
6 . The method as claimed in claim 3 wherein resistance R 1 is substantially 100K Ohms.
7 . An apparatus for measuring the conductance of a human or animal body, the apparatus including:
a first circuit including a first known resistance R 1 connected in series with the human body;
a first voltage switchable source E 1 interconnected to the first circuit;
a second voltage switchable source E 2 connected to the first circuit;
a voltage detector measuring the voltage across resistance R 1 ;
a controller interconnected to said voltage detector and said first and second switchable source, the controller switching a first source voltage E 1 into the first circuit and the voltage detector measuring the voltage V 1 across R 1 , the controller then switching a second source voltage E 2 and measuring a second voltage V 2 across the resistor R 1 , the controller than calculating a conductance S substantially in accordance with the equation:
S
=
(
V
2
-
V
1
)
R
1
(
E
2
-
E
1
)
-
(
V
2
-
V
1
)
.
8 . The apparatus as claimed in claim 7 wherein said controller interconnects source voltages E 1 , E 2 and calculates the corresponding conductance S in an iterative manner.