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The selective properties of regular track membranes
Nuclear Instruments and Methods in Physics Research A 359 (1995) 409-411
NUCLEAR INSTRUMENTS
LMETNOOS IN PNVSICS
RESEARCH SectIonA
EISEVIER
The selective properties of regular track membranes V.A. Brovkov
a, O.A. Makarov b3* , B.V. Mchedlishvili N.A. Timchenko d
‘, V.F. Pindyurin b,
a Institute of Semiconductor Devices, 634042 Tom& Russian Federation b Budker Institute of Nuclear Physics, 630090 Nouosibirsk, Russian Federation ’ Institute of Crystallography, I1 7333 Moscow, Russian Federation d Institute of Nuclear Physics at Tomsk Politechnical Uniuersity, 634050 Tomsk, Russian Federation Abstract Selective properties of regular track membranes, made by deep-etch X-ray lithography using synchrotron radiation of the VEPP3 storage ring, were studied. These membranes with a high porosity have practically no dispersion of the pore sizes and can find a number of useful applications.
1. Introduction The selective properties of porous materials, especially the membranes, are determined, first of all by the spread of their pore dimensions. This value for the commercial track membranes is, on the average, about 10% at the half-height of the distribution function. Certainly, the worst are the large size pores which are produced by the confluence of two or more adjoining pores (Fig. 1). There are two ways
* Corresponding author.
to avoid this disadvantage of track membranes. The first is to use membranes with a low porosity (about l-2%), or, which is practically the same, track membranes with two or more uncrossing systems of filtering channels, under the condition that the porosity of every system should not exceed l-2%. The second approach supposes the use of regular track membranes with a well determined regular system of pores of uniform shape. The selective properties of such regular track membranes (RTM), made by deep-etch X-ray lithography using synchrotron radiation of the VEPP-3 storage ring [l], are discussed in this paper.
Fig. 1. The lavsan track membrane (commercial sample) with bacteria and latex microparticles on the surface (S-10 km membrane thickness, 0.5 pm average size of the pores, + lo-15% pore size spread, 5-7% porosity). 0168-9002/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-9002(94)01669-O
IX. SR FOR MICROMECHANICS
V.A. BroukoLIet al. / Nucl. Instr. and Meth. in Phys. Res. A 359 (1995) 409-411
410
Fig. 2. The regular lavsan track membrane
(pilot sample: 6 p,rn membrane
thickness,
0.54 pm average pore size, +4%
or less pore size
spread, 23% porosity).
2. The RTM structure
and selective properties
The RTM structure was studied with a scanning electron microscope (SEMI. Fig. 2 demonstrates, as an example, a SEM microphotograph of a lavsan regular membrane of 6 p,rn thickness. Analysis of pore size measurements revealed a very good uniformity of the pores. The samples had two systems of pores: with an average diameter of 0.32 f 0.02 pm and 0.54 k 0.02 Frn. The average porosity was 20-25%. Both porous systems were placed on one sample. An example of a detailed pore size distribution for a porous system of 0.54 pm diameter is given in Fig. 3. The methods of optical diffraction showed the presence of a diffraction pattern corresponding to a period of the grating of about 1 km. The rigid colloidal particles were used for studying the RTM selective properties. There were vegetable and bacterial viruses with average dimensions of 0.03-0.1 pm,
latex and corundum microspheres of 0.2-1.0 km, and the deformable colloidal particles of the Pseudomonas diminutu bacteria with a 0.3 p,rn average particle dimension. The RTM selective properties were examined by penetrability of the microparticles, both for every system of pores with an average diameter of 0.32 km and 0.54 km, separately, and for a general system consisting of the two
-
$
0 0
0.5
ior commercial track nenbranes e0ctwr0 && ?f57Ae d = 0,8 x 2.4 pm.
- for prlot sanple5 of the ,-eQU/W track nenbranes Bacteria Pssudmonos Diminuto d * 0.3,um
1.0
1.5
Ratio A of a bacterial to a pore diameter
%%* 0 02
1.4
Size,
1.6
microns
Fig. 3. The histogram of a pore size distribution for the regular track membrane with a porous system of 0.54 p,rn diameter.
2.0
-
2.5
cell siie
Fig. 4. Dependence of the retaining factor cp for bacteria cells on the ratio A of minimum cell size to pore size, for the traditional filters (dark filled circles: bacteria E. coli, 0.8 X 2.4 wrn size) and the regular filters (non-filled circles: bacteria Pseudomonas diminuta, 0.3 Frn size).
VA Brovkov et al. /Nucl. Instr. and Meth. in Phys. Rex A 359 (1995) 409-411 indicated above. It was done with the purpose to demonstrate, under examination of the general system of 0.3-0.5 pm pores, the influence of the pore size dispersion on the selective properties of the membranes. The selectivity curve (the dependence of the selectivity, i.e., the degree of retaining the particles by pores, on the ratio of particle and pore dimensions) for the general system of 0.3-0.5 pm pore was, practically, the same, as for the commercial track membranes with the 0.3 pm average dimension of pores (Fig. 4). It was also shown that these membranes (both types) passed the bacteria of the Pseudomonas diminuta family, and, as a consequence, they were not sterilizing. In contrast to that, the RTM with 0.32 pm pore diameter retained all of these particles and was sterilizing. Moreover, careful examination of the RTM selectivity curve showed that, in this case, the separation was carried out in accordance with the principle “all or nothing” because the curve was extremely abrupt. The model particles with average sizes of about 0.3 pm and 0.5 pm did not penetrate, practically, through the RTMs with an average pore size of 0.32 pm and 0.54 pm, respectively.
411
3. Coaclusion
The results of the RTM selectivity properties investigations show that a high efficiency sterilization equipment can be developed on the basis of regular track membranes for, e.g., medicine, microbiology, and pharmacology. The RTM may turn out to be useful also as standard membranes with well determined selectivity properties for certification of other types of filters and for determining the size of microparticles.
Reference 111 L.D. Artamonova, V.N. Gashtold, G.A. Deis, G.N. Kulipanov, O.A. Makarov, LA. Mezentseva, S.I. Mishnev, V.P. Nazmov, V.F. Pindyurin, VS. Prokopenko, O.A. Redin, E.F. Reznikova, A.N. Skrinsky, V.V. Chesnokov and G.A. Cherkov, these Proceedings (10th Nat. Synchrotron Radiation Conf., Novosibirsk, Russia, 1994) Nucl. Instr. and Meth. A 359 (1995) 404.
IX. SR FOR MICROMECHANICS
NUCLEAR INSTRUMENTS
LMETNOOS IN PNVSICS
RESEARCH SectIonA
EISEVIER
The selective properties of regular track membranes V.A. Brovkov
a, O.A. Makarov b3* , B.V. Mchedlishvili N.A. Timchenko d
‘, V.F. Pindyurin b,
a Institute of Semiconductor Devices, 634042 Tom& Russian Federation b Budker Institute of Nuclear Physics, 630090 Nouosibirsk, Russian Federation ’ Institute of Crystallography, I1 7333 Moscow, Russian Federation d Institute of Nuclear Physics at Tomsk Politechnical Uniuersity, 634050 Tomsk, Russian Federation Abstract Selective properties of regular track membranes, made by deep-etch X-ray lithography using synchrotron radiation of the VEPP3 storage ring, were studied. These membranes with a high porosity have practically no dispersion of the pore sizes and can find a number of useful applications.
1. Introduction The selective properties of porous materials, especially the membranes, are determined, first of all by the spread of their pore dimensions. This value for the commercial track membranes is, on the average, about 10% at the half-height of the distribution function. Certainly, the worst are the large size pores which are produced by the confluence of two or more adjoining pores (Fig. 1). There are two ways
* Corresponding author.
to avoid this disadvantage of track membranes. The first is to use membranes with a low porosity (about l-2%), or, which is practically the same, track membranes with two or more uncrossing systems of filtering channels, under the condition that the porosity of every system should not exceed l-2%. The second approach supposes the use of regular track membranes with a well determined regular system of pores of uniform shape. The selective properties of such regular track membranes (RTM), made by deep-etch X-ray lithography using synchrotron radiation of the VEPP-3 storage ring [l], are discussed in this paper.
Fig. 1. The lavsan track membrane (commercial sample) with bacteria and latex microparticles on the surface (S-10 km membrane thickness, 0.5 pm average size of the pores, + lo-15% pore size spread, 5-7% porosity). 0168-9002/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-9002(94)01669-O
IX. SR FOR MICROMECHANICS
V.A. BroukoLIet al. / Nucl. Instr. and Meth. in Phys. Res. A 359 (1995) 409-411
410
Fig. 2. The regular lavsan track membrane
(pilot sample: 6 p,rn membrane
thickness,
0.54 pm average pore size, +4%
or less pore size
spread, 23% porosity).
2. The RTM structure
and selective properties
The RTM structure was studied with a scanning electron microscope (SEMI. Fig. 2 demonstrates, as an example, a SEM microphotograph of a lavsan regular membrane of 6 p,rn thickness. Analysis of pore size measurements revealed a very good uniformity of the pores. The samples had two systems of pores: with an average diameter of 0.32 f 0.02 pm and 0.54 k 0.02 Frn. The average porosity was 20-25%. Both porous systems were placed on one sample. An example of a detailed pore size distribution for a porous system of 0.54 pm diameter is given in Fig. 3. The methods of optical diffraction showed the presence of a diffraction pattern corresponding to a period of the grating of about 1 km. The rigid colloidal particles were used for studying the RTM selective properties. There were vegetable and bacterial viruses with average dimensions of 0.03-0.1 pm,
latex and corundum microspheres of 0.2-1.0 km, and the deformable colloidal particles of the Pseudomonas diminutu bacteria with a 0.3 p,rn average particle dimension. The RTM selective properties were examined by penetrability of the microparticles, both for every system of pores with an average diameter of 0.32 km and 0.54 km, separately, and for a general system consisting of the two
-
$
0 0
0.5
ior commercial track nenbranes e0ctwr0 && ?f57Ae d = 0,8 x 2.4 pm.
- for prlot sanple5 of the ,-eQU/W track nenbranes Bacteria Pssudmonos Diminuto d * 0.3,um
1.0
1.5
Ratio A of a bacterial to a pore diameter
%%* 0 02
1.4
Size,
1.6
microns
Fig. 3. The histogram of a pore size distribution for the regular track membrane with a porous system of 0.54 p,rn diameter.
2.0
-
2.5
cell siie
Fig. 4. Dependence of the retaining factor cp for bacteria cells on the ratio A of minimum cell size to pore size, for the traditional filters (dark filled circles: bacteria E. coli, 0.8 X 2.4 wrn size) and the regular filters (non-filled circles: bacteria Pseudomonas diminuta, 0.3 Frn size).
VA Brovkov et al. /Nucl. Instr. and Meth. in Phys. Rex A 359 (1995) 409-411 indicated above. It was done with the purpose to demonstrate, under examination of the general system of 0.3-0.5 pm pores, the influence of the pore size dispersion on the selective properties of the membranes. The selectivity curve (the dependence of the selectivity, i.e., the degree of retaining the particles by pores, on the ratio of particle and pore dimensions) for the general system of 0.3-0.5 pm pore was, practically, the same, as for the commercial track membranes with the 0.3 pm average dimension of pores (Fig. 4). It was also shown that these membranes (both types) passed the bacteria of the Pseudomonas diminuta family, and, as a consequence, they were not sterilizing. In contrast to that, the RTM with 0.32 pm pore diameter retained all of these particles and was sterilizing. Moreover, careful examination of the RTM selectivity curve showed that, in this case, the separation was carried out in accordance with the principle “all or nothing” because the curve was extremely abrupt. The model particles with average sizes of about 0.3 pm and 0.5 pm did not penetrate, practically, through the RTMs with an average pore size of 0.32 pm and 0.54 pm, respectively.
411
3. Coaclusion
The results of the RTM selectivity properties investigations show that a high efficiency sterilization equipment can be developed on the basis of regular track membranes for, e.g., medicine, microbiology, and pharmacology. The RTM may turn out to be useful also as standard membranes with well determined selectivity properties for certification of other types of filters and for determining the size of microparticles.
Reference 111 L.D. Artamonova, V.N. Gashtold, G.A. Deis, G.N. Kulipanov, O.A. Makarov, LA. Mezentseva, S.I. Mishnev, V.P. Nazmov, V.F. Pindyurin, VS. Prokopenko, O.A. Redin, E.F. Reznikova, A.N. Skrinsky, V.V. Chesnokov and G.A. Cherkov, these Proceedings (10th Nat. Synchrotron Radiation Conf., Novosibirsk, Russia, 1994) Nucl. Instr. and Meth. A 359 (1995) 404.
IX. SR FOR MICROMECHANICS