Journal of Minerals & Materials Characterization & Engineering, Vol. 8, No. 9, pp 679-692, 2009
jmmce.org Printed in the USA. All rights reserved
679
Effect of Electrets Property on Artificially Removed Human Renal Stone
Mineral Compositions
G. Kanchana, P. Sundaramoorthi*, G.P. Jeyanthi
Department of Bio-chemistry, Avinashilingam University for Women, Coimbatore, India.
*Department of Physics, Thiruvalluvar Govt. Arts College, Rasipuram, Namakkal,
India-637401.
(Ph.No.-04286-266313 (off.) Fax- 04286-266323 , MailID-moorthi.sundara@gmail,com)
ABSTRACT
Electrical and thermal conductivity studies play a vital role in the field of science and
technology. According to the conductivity terms, materials can be classified in to good
conductors, bad conductors, semiconductors and super conductors. In the free electron theory,
electron only acts as carrier and carries its energy from one point to another point either natural
or forced. In the present investigation, five renal stones are collected from the poor hard
working males who are affected with mineral deposition in the urinary tracts. The stones are
collected from the hospital by Lithotropic treatment process. Using two- probes method, the
electrical conductivities are measured at different temperatures. The thermal conductivity and
temperature coefficients are calculated. The results are reported and discussed.
Key Words: Mineral processing, Sampling, Process instrumentation, Bio-oxidation, Ion
exchange
1. INTRODUCTION
The conductivity of many biomaterials has been reported [1]. The applied problems, such as
thrombogenesis and enzymatic activity of cytochrome oxides, have been dealt with either semi
conductivity or electrets behavior of different biomaterials. In the present study, both these
aspect have been attempted on the same materials, namely renal stones or renal calculi. The
study of electrets behaviors and conductivity becomes essential in order to find an inhibitor for
renal stones or prevent its growth. The electrets behavioral of the renal stone material were

680 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
studied through TSD, TSP [2-4]. Here the investigators report the D.C conductivity of kidney
stones as a function of temperature and applied electric field and its interpretations.
2. MATERIALS AND METHODS
Kidney stones are removed from the affected patients by Litho tropic process in the Rasi stones
diagnosing center in Rasipuram, Namakkal, India, and are used in the present investigations.
These stones constituents are analyzed by biochemical analysis process. Table 1 represents the
chemical composition present in the renal stones
Table 1. Chemical composition present in the renal stones
Stones Chemical constituents
A Calcium phosphate.
B Calcium oxalate, mono di-hydrate.
C Calcium oxalate monohydrate with Phosphates.
D Calcium oxalate mono, di-hydrate, Phosphate,
E Calcium oxalate monohydrate
Figure 1. Stone A Figure 2. Stone B.
Stone samples are prepared for conductivity measurement initially. The bloodstains and other
impurities are removed from the surfaces of the sample and dried naturally. Then the sample
surfaces are smoothened by using very thin grain grinder. The renal stone samples are placed in
between two aluminum probes with deep contact. The sample holders with the sample are kept

Vol.8, No.9 Effect of Electrets Property 681
inside the micro oven, which is automatically heated with electronic temperature monitor and
controller (the accuracy is 2oC). The D.C conductivity is studied at the temperature (T) from 295
K to373K at irregular temperature intervals. The electric field applied to the probes starts from
1V to 12V and the corresponding currents are measured. The entire samples are kept at a
particular temperature at least 15 minutes to reach the saturation. Then the measurements are
started. At higher voltage and higher temperature the current settling time are observed. The
transient current of the sample mainly depends upon the presence of carriers in a sample
according to the Curie-Von-Schweidlar law. The conductivity has been reported for polymer
samples [6-8] and ionic materials [9-10].
Figure 3. Stone C. Figure 4. Stone D.
Figure 5. Stone E.

682 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
3. RESULTS
The approximate area of each samples are measured by using graph sheet. The temperatures are
varied from 295K to 373 K. The applied voltage (V), corresponding current measurements (I),
resistance (R), resistivity (ρ), conductivity (σ) and current density (J) of each sample at a
particular temperature are reported in Tables 2 to 16.
Table 2. Electrets properties of renal stone A at 33oC, A=30x10-6 m2, L=5x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured
in micro -amperes
(I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 3 0.667 3960 0.5052
2 4 3 1.333 7980 0.5013
3 6 4 1.500 9000 0.6670
4 8 5 1.600 9600 0.8333
5 10 6 1.667 1002 0.9999
6 12 8 1.500 9000 1.3333
1.378 8257 0.8060
Co efficient of electrical conductivity (σ) = 1.211x10-4 mho.m-1
Table 3. Electrets properties of renal stone A at 62°C, A=30x10-6 m2, L=5x10-3m
S.NO Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
in 106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 2 1.000 6000 0.3333
2 4 2 2.000 12000 0.3333
3 6 3 2,000 12000 0.3333
4 8 4 2.000 12000 0.3333
5 10 5 2.000 12000 0.3333
6 12 6 2.000 12000 0.3333
2.000 11000 0.3333
Co efficient of electrical conductivity (σ) =0.909x10-4 mho.m-1

Vol.8, No.9 Effect of Electrets Property 683
Table 4. Electrets properties of renal stone A at 96oC, A=30x10-6 m2, L=5x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 2 1.000 6000 0.3333
2 4 2 2.000 12000 0.3333
3 6 3 2.000 12000 0.5000
4 8 3 2.667 16002 0.4999
5 10 4 2.580 15000 0.6670
6 12 4 3.000 18000 0.6667
2.208 13167 0.3888
Co efficient of electrical conductivity (σ) =0.759x10-4 mho.m-1
Table 5. Electrets properties of renal stone B at 32oC, A=30x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. M (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 5 0.4000 1600 1.2500
2 4 6 0.6667 2668 1.4999
3 6 8 0.7500 3000 2.0000
4 8 10 0.8000 3200 2.5000
5 10 12 0.8333 3332 3.0000
6 12 14 0.8571 3428 3.5000
0.7176 2871 2.2900
Co efficient of electrical conductivity (σ) =3.483 x10-4 mho.m-1

684 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
Table 6. Electrets properties of renal stone B at 64oC, A=30x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 4 0.500 2000 1.0000
2 4 4 1.000 4000 1.0000
3 6 5 1.200 4800 1.2500
4 8 6 1.333 5332 1.5000
5 10 8 1.250 5000 2.0000
6 12 10 1.200 4800 2.5000
1.091 4322 1.5420
Co efficient of electrical conductivity (σ) =2.313 x 10-4 mho.m-1
Table-7 Electrets properties of renal stone B at 99oC, A=30x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 3 0.667 2668 0.7490
2 4 3 1.333 5320 0.7200
3 6 4 1.500 6000 1.0000
4 8 4 2.000 8000 1.0000
5 10 5 2.000 8000 1.2500
6 12 6 2.000 8000 1.5000
1.583 6331 1.0370
Co efficient of electrical conductivity (σ) =1.579 x 10-4 mho.m-1

Vol.8, No.9 Effect of Electrets Property 685
Table-8 Electrets properties of renal stone C at 33oC, A=25x10-6 m2, L=5x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 10 0.200 1000 2.0000
2 4 12 0.333 1665 2.4000
3 6 13 0.462 2310 2.6000
4 8 15 0.533 2665 3.0000
5 10 17 0.588 2940 3.4000
6 12 20 0.600 3000 4.0000
0.453 2263 2.9000
Co efficient of electrical conductivity (σ) =4.418 x 10-4 mho.m-1
Table-9 Electrets properties of renal stone C at 64oC, A=30x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 9 0.222 1110 1.8000
2 4 10 0.400 2000 2.0000
3 6 13 0.462 2310 2.5800
4 8 13 0.615 3075 2.6010
5 10 14 0.714 3570 2.8000
6 12 14 0.857 4285 2.8000
0.545 2725 2.4300
Co efficient of electrical conductivity (σ) =3.669x 10-4 mho.m-1

686 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
Table-10 Electrets properties of renal stone C at 95oC, A=25x10-6 m2, L=5x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 6 0.333 1650 1.2000
2 4 6 0.666 3330 1.2000
3 6 7 0.857 4285 1.4000
4 8 7 1.143 5715 1.3999
5 10 7 1.429 7145 1.3999
6 12 8 1.500 7500 1.6000
0.988 4938 1.3670
Co efficient of electrical conductivity (σ) =2.025x 10-4 mho.m-1
Table-11 Electrets properties of renal stone D at 34oC, A=12x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 16 0.126 252 7.9400
2 4 18 0.222 444 9.0000
3 6 24 0.250 500 12.0000
4 8 28 0.286 572 13.9900
5 10 32 0.313 626 15.9700
6 12 35 0.343 686 17.4900
0.257 513 12.9300
Co efficient of electrical conductivity (σ) =19.493x 10-4 mho.m-1

Vol.8, No.9 Effect of Electrets Property 687
Table-12 Electrets properties of renal stone D at 65oC, A=12x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 10 0.200 400 5.0000
2 4 12 0.333 666 6.0060
3 6 16 0.375 750 8.0000
4 8 16 0.500 1000 8.0000
5 10 17 0.588 1176 8.5000
6 12 20 0.600 1200 10.0000
0.433 865.33 7.5840
Co efficient of electrical conductivity (σ) =11.556x 10-4 mho.m-1
Table-13 Electrets properties of renal stone D at 99oC, A=12x10-6 m2, L=6x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 6 0.333 666 3.0000
2 4 6 0.667 1334 2.9000
3 6 7 0.857 1714 3.5000
4 8 7 1.143 2286 3.4900
5 10 7 1.428 2856 3.5000
6 12 10 1.200 2400 5.0000
0.938 1876 3.5800
Co efficient of electrical conductivity (σ) =5.33x 10-4 mho.m-1

688 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
Table-14 Electrets properties of renal stone E at 35oC, A=15x10-6 m2, L=3x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106 (Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 8 0.250 1250 1.6000
2 4 8 0.500 2500 1.6000
3 6 9 0.667 3350 1.8100
4 8 9 0.889 4445 1.7800
5 10 11 0.909 4545 2.2000
6 12 11 1.091 5455 2.1900
0.718 3590 1.8600
Co efficient of electrical conductivity (σ) =2.785x 10-4 mho.m-1
Table-15 Electrets properties of renal stone E at 65oC, A=15x10-6 m2, L=3x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. M (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 7 0.286 1430 1.3990
2 4 8 0.550 2500 1.6000
3 6 8 0.750 3750 1.6000
4 8 9 0.889 4445 1.7999
5 10 10 1.000 5000 2.0000
6 12 10 1.200 6000 2.0000
0.771 3854 1.7300
Co efficient of electrical conductivity (σ) =2.594x 10-4 mho.m-1

Vol.8, No.9 Effect of Electrets Property 689
Table-16 Electrets properties of renal stone E at 98oC, A=15x10-6 m2, L=3x10-3m
S.NO
Voltage applied
in Volts (V).
Current measured in
micro -amperes (I).
Resistance
106
(Ohm).
Resistivity in
Ohm. m (ρ).
Current
density (J) x
10-4 Amp/m2
1 2 5 0.400 2000 3.6000
2 4 5 0.800 4000 7.2000
3 6 6 1.000 5000 10.8000
4 8 6 1.333 6665 14.4000
5 10 7 1.429 7145 18.0000
6 12 7 1.714 8570 21.6000
1.112 5563 12.6000
Co efficient of electrical conductivity (σ) =1.798 x 10-4 mho.m-1
4. RESULT AND DISCUSSION
The measurement of hall coefficient of the renal stones is very difficult. The stones containing
collagens like micro-protein and apatite also have some organic matrix like protein at 5% of the
total weight [13]. The protein matrix is clearly visible under a scanning microscope. The D.C
electrical conductivity of the renal stones are compared and calculated with the standard ionic
conductors [11] and semiconductors [12].
The ionic conduction for the renal stone is
σ=σ1exp(A/KT)+σ2exp(-B/KT)
Where σ1,σ2 are the zero field conductivity, A and B are constants. The two exponential terms
are nature of normal conductors.
In semiconductors the conductivity
σ=σ0exp(-Eg/2KT)
Here σ0 is the zero field conductivity and Eg is the activation energy of the conductors at a
particular temperature (T). Because of practical inconvenience of electron microscope (SEM), a
fine powder of kidney stone was observed under a high resolution optical microscope and shows
fibrils of protein. Thus renal stones can be regarded as a mixture of semi conducting materials
like N type and P type, but totally it behaves like N type material or conductors. Hence,
conductivity of a kidney stone shows it may be interpreted in terms of a partially compensated
semiconductor.

690 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
Available mechanism for conduction of renal stones may be sought with the help of various
scattering mechanism of conductors and semiconductors [14]. The conductivity of samples
depends upon the scattering by lattice vibrations. In conductor the curve between conductivity
and temperature should be straight line, but in semiconductor, it is not in usual [15].
The TSP, TSD data of kidney stones also give added information about its conduction
mechanism [2, 3]. For the TSP, TSD conductivity of a sample, the changing current is composed
of three components, which are conduction, polarization and depolarization. When temperature
increases, the conductivity of a samples is increased, the polarization and depolarization peaks
merge in the conduction current or only a part of it is observable [16]. The voltage dependence
of conductivity decreases with rise of temperature (T). The current density decreases, which
shows the conduction is in non-ohmic. This change suggests a warm electron effect [17]. At
higher temperature, the current density is directly proportional to voltage and gives the ohmic
behaviors. This is clear that for a sample at higher temperature, the thermal energy difference
between the charge carriers and lattices are relatively low or due to asymmetric effect [18]
formed in inside the crystals of calcium oxalates and calcium phosphates. All the calculated renal
stone parameters are tabulated in the following tables.
Table-17 Electrical parameters of renal stone samples
SNo Stones Temperature
in degree
Celsius
R in 106
ohms
ρ
Ohm-meter
J x10-4
Ampere/met2
1 A 33 1.378 8257 0.8060
62 1.833 11000 0.3333
98 2.208 13167 0.3888
2 B 32 0.718 2871 2.2990
64 1.091 4322 1.5420
99 1.583 6331 1.0370
3 C 33 0.453 2263 2.9000
64 0.545 2725 2.4300
98 0.988 4958 1.3670
4 D 34 0.256 513 12.9300
65 0.433 865.3 7.5840
99 0.938 1876 3.5800
5 E 35 0.718 3590 1.8600
64 0.771 3853 1.7300
98 1.112 5563 12.6000

Vol.8, No.9 Effect of Electrets Property 691
Table-18 Thermal conductivity of renal stones at different temperature.
[Loraznts constant ( Lz )= 2.44x 10-8 wΩk-2]
SNo Name of the
Stone
samples
Conductivity
(σ) X10-4
mho.m-1
Temperature
in degree Celsius
Thermal
conductivity
K= σLzT X10-9
W/MK
1 A 1.211 33 0.904
0.909 62 0.743
0.759 98 0.687
2 B 3.483 32 2.592
2,313 64 1.902
1.579 99 1.433
3 C 4.418 33 3.298
3.669 64 3.016
2.025 98 1.833
4 D 19.49 34 14.60
11.56 65 9.530
5.333 99 4.838
5 E 2.785 35 2.093
2.594 64 2.133
1.798 98 1.619
Table-19 Temperature coefficient of the renal stone at different temperatures
Sample Temperature
minimum in
degree Celsius
Temperature
Maximum in
degree Celsius
Temperature coefficient
of the sample.
α=(R2-R1)/(R1T2-R2T1)
A 33 62 0.01825
33 98 0.01334
B 32 64 0.03390
32 99 0.04244
C 33 64 0.00841
33 98 0.04556
D 34 65 0.09228
34 99 0.10415
E 35 64 0.00279
35 98 0.01253

692 G. Kanchana, P. Sundaramoorthi, G.P. Jeyanthi Vol.8, No.9
5. CONCLUSION
All the renal stones thermal conductivity, electrical conductivity and temperature co-efficient are
measured. At higher temperature, the thermal conductivity of all the samples is constant, but the
electrical conductivity varied. All the stones are positive temperature coefficient materials. The
entire samples are high conductivity at low temperature, but when the temperature increases, the
conductivity decreases.
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