Abstract
The swelling equilibrium of gels can be explained by the Flory-Rehner theory. The FR theory calculates the difference of the chemical potential of a solvent inside a gel to the surrounding pure solvent as a sum of the mixing and the elastic part. The first is based on the Flory–Huggins theory, the second on the rubber elasticity theory (Sect. 1). An important role for gels with volume phase transition plays the Flory–Huggins interaction parameter and its dependencies on temperature and concentration. In a system with specific interactions between the solvent and the network, additional contributions to the chemical potential have to be taken into consideration. The application of hydrogels is based on changes of the gel properties, mostly the dramatic change of their swollen volume, in response to specific environmental stimuli. The velocity of changes of the degree of swelling is of outstanding importance. The kinetics of swelling and shrinking is determined by different diffusion processes (Sect. 2). The cooperative motion of the net chains is characterized by a cooperative diffusion coefficient D coop . The time dependence of the degree of swelling for gels of different geometries is followed and D coop calculated. Processes happening at the volume phase transition were discussed. Section 3 introduces then the fundamental concepts of the spectroscopic characterization of hydrogels. The focus of Sect. 3.1 is a practical hands-on advice that everyday practitioners of infrared and Raman spectroscopy will find useful. The reader will be introduced to spectroscopic methods and to sample preparation techniques. More advanced techniques like imaging spectroscopy and chemometric data analysis are discussed. Section 3.2 discusses the NMR imaging technique as an important method to visualize swelling-related processes in hydrogels.
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Notes
- 1.
It was observed, that a gel swollen to equilibrium in the liquid solvent shrinks as soon as it is transferred to the vapour phase of the same solvent. This phenomenon is known as the “paradox of Schroeder” (Freundlich 1932). For a theory of swelling with solvents in various phases, see (Borchard & Steinbrecht 1991).
- 2.
Also, the swelling can be measured as the equilibrium water fraction EWF, defined as the wet weight fraction of swollen gel:
EWF = [(weight of swollen gel) – (weight of dry gel)]/[weight of swollen gel]; \( {\rm \varphi_2}\, = \,{{\left( {1 - EWF} \right)\,{\rho_1}} \mathord{\left/{\vphantom {{\left( {1 - EWF} \right)\,{\rho_1}} {\left[ {{\rho_1}\, + \,EWF\,\left( {{\rho_2}\, - \,{\rho_1}} \right)} \right]}}} \right.} {\left[ {{\rho_1}\, + \,EWF\,\left( {{\rho_2}\, - \,{\rho_1}} \right)} \right]}}\, \)
- 3.
Other values for Δs and Δh were given in (Shibayama et al. 1994a):
Δs = −2.8 10−23 J/K; Δh = –6.5 10−21 J
- 4.
Changes in the Gibbs (G) and the Helmholtz (\( F\, = \,f(T,V,{n_1},\,{n_2}\,) \)) free energies are assumed to be equivalent since the product pΔV is small at low pressures.
- 5.
The cycle rank ξ, or number of independent circuits, characterizes the network with greater generality, regardless of the nature of its imperfection. ξ is the minimum number of scissions required to reduce the network to a spanning tree.
- 6.
Uniaxial means: λx = λ; λ y = λ z = λ −1/2 ; λ = x/x 0 with x 0 the un-deformed and x the deformed length, respectively.
- 7.
The mole number of net chains is n c = N c/NL = m/M c, where m is the mass of the network. The density of the network is ρ2 = m/V o.
- 8.
It is possible to use the volume of the polymer in the state of preparing the network as a reference. The deformation of the network by swelling is then measured as the ratio of the swollen volume to the volume at preparation, see Chapter 1. This quantity is called as swelling ratio.
- 9.
The memory term describes the changes of the network chain conformation in a solution at a concentration of the reacting system to the conformation in a dry state (reference state).
- 10.
The ratio of the characteristic relaxation time to the characteristic diffusion time is the so-called Deborah number (De). The smaller De is, the more fluidic the material appears.
- 11.
A solution of 20 wt-% polymer in water was irradiated with a dose of 80 kGy.
- 12.
A gel consists of polymer chains, cross-links and solvent. The polymer chains undergo Brownian motion while the cross-links remain at the same position. Light scattered from gels therefore has a dynamic and a static contribution. The scattering by chain segments resulting in an exponential decay of the scattering field is called homodyne scattering. Contrary, cross-links behave as local oscillators and do not produce any decay of the scattering field. This non-decaying component heterodynes with the decaying part and is called heterodyne scattering.
- 13.
For an ergodic system the long-time average is equal to the ensemble average – the average with respect to the configuration of the systems (average over all possible positions and shapes).
- 14.
Contrast means a difference in NMR signals which enables us to identify and to observe a defined species in an ensemble of other species.
Abbreviations
- AMTIR-1:
-
Ge33As12Se55 glass
- ANN:
-
Artificial neural network
- ATR:
-
Attenuated total reflectance
- BaF2 :
-
Barium fluoride glass
- CA:
-
Cluster analysis
- CaF2 :
-
Calcium fluoride glass
- CCD:
-
Charge-coupled device
- CH3OD:
-
Per-deuterated methanol
- D2O:
-
Deuterium oxide (heavy water)
- DC:
-
Direct current
- DLS:
-
Dynamic light scattering
- EWF:
-
Equilibrium water fraction
- FA:
-
Factor analysis
- FESEM:
-
Field emission scanning electron microscopy
- FPA:
-
Focal plane array
- FT-IR:
-
Fourier transform infrared spectroscopy
- GAR:
-
Grazing angle reflectance
- Ge:
-
Germanium
- IR:
-
Infrared
- KBr:
-
Potassium bromide
- LDA:
-
Linear discriminant analysis
- MBAAm:
-
N, N’-methylene bisacrylamide
- NMR:
-
Nuclear magnetic resonance
- PAAc:
-
Poly(acrylic acid)
- PCA:
-
Principal components analysis
- PEG:
-
Poly(ethylene glycol)
- PLS:
-
Partial least squares
- PNIPAAm:
-
Poly(N-isopropyl acrylamide)
- PVA:
-
Poly(vinyl alcohol)
- PVME:
-
Poly(vinyl methyl ether)
- PVP:
-
Poly(vinyl pyrrolidone)
- RET:
-
Rubber elasticity theory
- NMR:
-
Nuclear magnetic resonance
- Si:
-
Silicon
- UV:
-
Ultraviolet
- Vis:
-
Visible
- ZnS:
-
Zinc sulfide
- ZnSe:
-
Zinc selenide
- A :
-
Area
- A0 :
-
Structure factor (RET)
- a1 :
-
Correction term
- B:
-
Volume factor (RET)
- B 0 :
-
Static magnetic field power
- B1 :
-
Intercept
- c :
-
Concentration
- c* :
-
Overlap concentration
- d :
-
Diameter of gel cylinder
- D :
-
Diffusion coefficient
- D coop :
-
Cooperative diffusion coefficient
- d p :
-
Depth of penetration
- E :
-
Young's modulus
- f :
-
Functionality of junction points
- f :
-
Friction coefficient
- f:
-
Force
- F :
-
Free energy (intensive, with index)
- G :
-
Gradient of magnetic field
- G :
-
Free enthalpy (intensive, with index)
- G :
-
Shear modulus
- g (1)(t):
-
Electric field correlation function
- g (2)(t):
-
Intensity correlation function
- H :
-
Enthalpy
- I F :
-
Scattering intensity for thermal fluctuations
- k :
-
Cylinder diameter; disc thickness
- K :
-
Bulk modulus
- K(λ):
-
Hindrance of fluctuation (constraint function)
- kB :
-
Boltzmann constant (1.381×10−23 J K−1)
- m :
-
Mass
- M :
-
Molecular weight
- M c :
-
Molecular weight of network chain
- n :
-
Number of moles
- n :
-
Refractive index
- n S :
-
Refractive index of the sample
- nC :
-
Refractive index of the ATR crystal
- N :
-
Number of molecules or particles
- N 0 :
-
Number of monomers
- NL :
-
Avogadro number (6.022×1023 mol−1)
- p :
-
Pressure
- q :
-
Scattering vector
- q 2/3 :
-
Memory-term
- Q :
-
Degree of swelling
- Q m :
-
Mass degree of swelling
- Q v :
-
Volume degree of swelling
- R:
-
Gas constant (8.314 J K−1 mol−1)
- r :
-
Radius
- r:
-
Rocking vibration
- R h :
-
Hydrodynamic radius
- S :
-
Entropy (intensive)
- s:
-
Scissoring vibration
- T :
-
Tempereture
- t :
-
Delay time
- t:
-
Twisting vibration
- T 1 :
-
Relaxation time
- T 2 :
-
Relaxation time
- T c :
-
Critical temperature
- T g :
-
Glass transition temperature
- t lag :
-
Time-lag
- u:
-
Displacement
- \( \overline {V_i} \) :
-
Partial molar volume of component i
- V i :
-
Molar volume of component i
- x,y,z:
-
Space coordinate
- X P :
-
Fraction of dynamically scattered light
- \( \langle \rangle \) :
-
Time average
- \( {\left\langle I \right\rangle_{t,P}} \) :
-
Total time-averaged scattering intensity at a constant sample position
- α:
-
angle of incidence
- γ :
-
Gyro-magnetic ratio
- Γ:
-
First cummulant
- δ :
-
Deformation vibration
- δ(u):
-
Displacement
- Δ:
-
Total change
- Δx:
-
Spatial resolution
- Δω :
-
Width of resonance line
- ηs :
-
Viscosity of solvent
- Θ :
-
Theta condition
- θ :
-
Scattering angle
- λ:
-
Extension ratio relative to isotropic state of reference
- λ0 :
-
Wavelength of the incident light
- μ:
-
Poisson´s ratio
- μ i :
-
Chemical potential of component i
- μJ :
-
Number of junction points
- ν :
-
Stretching vibration
- ν :
-
Wavenumber
- ν as :
-
Antisymmetrical stretching vibration
- ν s :
-
Symmetrical stretching vibration
- νc :
-
Cross-linking density (mol network chains / volume)
- ξ:
-
Cycle rank
- ξ:
-
Screening length
- π:
-
Osmotic pressure, swelling pressure
- σ:
-
Stress, force per area of un-deformed sample
- τ :
-
Relaxation time
- ϕA :
-
Volume fraction swelling agent
- ϕ:
-
Volume fraction
- χ:
-
Huggins interaction parameter
- ω :
-
Resonance frequency of the signal
- ω:
-
Wagging vibration
- 0:
-
Reference state
- 1:
-
Solvent
- 2:
-
Polymer
- c :
-
Cross-linked
- cr :
-
Critical
- d :
-
Dry, unswollen
- dry :
-
Dry state
- el :
-
Elastic
- exp :
-
Measured quantity
- lo :
-
Longitudinal
- m :
-
Medium intensity of the vibration mode
- m :
-
Mixing
- net :
-
Network
- P :
-
Sample position
- Q :
-
Swollen state
- s :
-
Swollen
- tr :
-
Transversal
- u :
-
Uncross-linked
- v :
-
Strong intensity of the vibration mode
- VPT:
-
Volume phase transition temperature
- vs :
-
Very strong intensity of the vibration mode
- w :
-
Weak intensity of the vibration mode
References
Alfrey T Jr, Gurnee EF, Lloyd WG (1966) Diffusion in glassy polymers. J Polym Sci C (Polymer Symp) 12:249–261
Arndt K-F, Richter A, Ludwig S, Zimmermann J, Kressler J, Kuckling D, Adler H-J (1999) Poly(vinyl alcohol)/poly(acrylic acid) hydrogels: FT-IR spectroscopic characterization of crosslinking reaction and work at transition point. Acta Polym 50:383–390
Arndt K-F, Schmidt T, Menge H (2001) Poly(vinyl methyl ether) hydrogel formed by high energy irradiation. Macromol Symp 164:313–322
Arndt K-F, Knoergen M, Richter S, Schmidt T (2006) NMR Imaging: monitoring of swelling of environmental sensitive hydrogels. In: Webb GA (ed) Modern Magnetic Resonance, Part 1. Springer, Dordrecht
Arndt K-F, Knörgen M, Richter S, Schmidt T (2006b) NMR imaging: monitoring of swelling of environmental sensitive hydrogel. In: Webb GA (ed) Modern Magnetic Resonance. Springer, Dordrecht
Bajpai SK, Bajpai M, Sharma L (2007) Inverse suspension polymerization of poly(methacrylic acid-co-partially neutralized acrylic acid) superabsorbent hydrogels: synthesis and water uptake behavior. Desig Monom Polym 10:181–192
Baumgartner S, Lahajnar G, Sepe A, Kristl J (2005) Quantitative evaluation of polymer concentration profile during swelling of hydrophilic matrix tablets using 1H NMR and MRI methods. Europ J of Pharmaceutics and Biopharmaceutics 59:299–306
Bhargava R, Levin IW (2005) Spectrochemical analysis using Infrared multichannel detectors. Blackwell, Oxford
Blümlich B (2000) NMR Imaging of Materials. Oxford University press, Oxford
Blümich B, Casanova F (2006) Mobile NMR. In: Webb GA (ed) Modern Magnetic Resonance. Part 1. Springer, Dordrecht
Borchard W, Steinbrecht U (1991) Colloid Polym Sci 269:95
Callaghan PT (1991) Principles of Nuclear Magnetic Resonance microscopy. Oxford University Press, Oxford
Chiarelli P, Domenica C, Genuini G (1993) Crazing dynamics in the swelling of thermally crosslinked poly(vinyl alcohol)–poly(acrylic acid) films. J Material Sci: Materials in Medicine 4:5–11
da Costa A, Amado AM (2001) Cation hydration in hydrogel polyacrylamide-phosphoric acid network: a study by Raman spectroscopy. Solid State Ionics 145:79–84
Dong LC, Hoffman AS (1990) Synthesis and application of thermally-reversible heterogels for drug delivery. J Controlled Release 13:21–31
Dušek K, Patterson D (1968) Transition on swollen polymer networks induced by intramolecular condensation. J Polym Sci A-2(6):1209–1216
Eckert F (2003) Bestimmung der kooperativen Diffusionskoeffizienten von Poly (acrylsäure)-Netzwerken. Diploma thesis, TU Dresden.
Erman B, Flory PJ (1978) Theory of elasticity of polymer networks.II. The effect of geometric constraints on junctions. J Chem Phys 68:5363–5369
Ferraro JR, Nakamoto K (1994) Introductory Raman spectroscopy. Academic Press, San Diego
Flory PJ (1942) Thermodynamics of high-polymer solutions. J Chem Phys 10:51–61
Flory PJ (1944) Network structure and the elastic properties of vulcanized rubber. Chem Rev 35:51–75
Flory PJ (1953) Principles of Polymer Chemistry. Cornell University Press, Ithaca NY
Flory PJ (1976) Statistical thermodynamics of random networks. Proc Royal Soc London A 351(1666):351–380
Flory PJ (1977a) Theory of elasticity of polymer networks. The effect of local constraints on junctions. J Chem Phys 66:5720–5729
Flory PJ (1977b) The molecular theory of rubber elasticity. Contemp Top Polym Sci 2:1–18
Flory PJ, Rehner J Jr (1943a) Statistical mechanics of cross-linked polymer networks. I. Rubberlike elasticity. J Chem Phys 11:512–520
Flory PJ, Rehner J Jr (1943b) Statistical mechanics of cross-linked polymer networks. II. Swelling. J Chem Phys 11:521–526
Freundlich H (1932) Kapillarchemie, Vol 2. Akad Verlagsges mbH, Leipzig, p 567
Ganapathy S, Rajamohanan PR, Badiger MV, Mandhare AB, Mashelkar RA (2000) Proton magnetic resonance imaging in hydrogels: volume phase transition in poly(N-isopropylacryl-amid. Polymer 41:4543–4547
Garton A (1992) Infrared Spectroscopy of polymer blends, composites and surfaces. Hanser, Munich
Gehrke SH (1993) Synthesis, equilibrium swelling, kinetics, permeability and applications of environmentally responsive gels. Adv Polym Sci 110:81–144
George KA, Wentrop-Byrne E, Hill DJT, Whittaker AK (2004) Investigation into the diffusion of water into HEMA-co-MOEP hydrogels. Biomacromolecules 5:1194–1199
Ghi PY, Hill DJ, Maillet D, Whittaker AK (1997a) N.m.r. imaging of the diffusion of water into poly(tetrahydrofufuryl methacrylate-co-hydroxyethylmethacrylate). Polymer 38:3985–3989
Ghi PJ, Hill DJT, Maillet D, Whittaker AK (1997b) N.m.r. imaging of the diffusion of water into poly(tetrahydrofurfuryl methacrylate-co-hydroxyethyl methacrylate). Polymer 38:3985–3989
Gotoh T, Nakatani Y, Sakohara S (1998) Novel synthesis of thermosensitive porous hydrogels. J Pol Sci 69:895–906
Griffiths PR, de Haseth JA (2007) Fourier Transform Infrared Spectroscopy. Wiley, Hoboken
Günzler H, Gremlich HU (2002) IR Spectroscopy. Wiley-VCH, Weinheim
Guo Y, Peng Y, Wu P (2008) A two-dimensional correlation ATR-FTIR study of poly(vinyl methyl ether) water solution. J Molec Structure 87:486–492
Hermans JJ (1947) Deformation and swelling of polymer networks containing comparatively long chains. Trans Faraday Soc 43:591–600
Hirotsu S (1991) Softening of bulk modulus and negative Poisson's ratio near the volume phase transition of polymer gels. J Chem Phys 94:3949–3957
Hirotsu S, Hirokawa Y, Tanaka T (1987) Volume-phase transitions of ionized N-isopropylacrylamide gels. J Chem Phys 87:1392–1395
Hotta Y, Ando I (2002) A study of shrinkage process of a polymer gel under electric field by 1H NMR imaging method using an NMR cell with thin platinum electrodes. J Molec Structure 602–603:165–170
Huggins ML (1941) Solutions of long-chain compounds. J Chem Phys 9:440
Huggins ML (1943) Thermodynamic properties of solutions of high polymers. The empirical constant in the activity equation. Ann N Y Acad Sci. 44:431–443
James HM, Guth E (1943) Theory of the elastic properties of rubber. J Chem Soc 11:455–481
Knörgen M, Heuert U, Schneider H, Heinrich G (1999) NMR relaxation and NMR imaging of elastomers in the course of thermal aging. J Macromol Sci Phys B38:1009–1022
Knörgen M, Arndt K-F, Richter S, Kuckling D, Schneider H (2000) Investigation of swelling and diffusion in polymers by 1H NMR imaging: LCP networks and hydrogels. J Molec Struc 554:69–79
Kuckling D, Adler H-J P, Arndt K-F (2003) Poly(N-isopropylacrylamide) copolymers: hydrogel formation via photocrosslinkling. In: Bohidar HB, Dubin P, Osada Y (eds) Polymer Gels: fundamentals and applications, ACS Symp Ser 833. ACS, Washington
Kwak S, Lafleur M (2003) Raman spectroscopy as a tool for measuring mutual-diffusion coefficients in hydrogels. Appl Spectroscopy 57:768–773
Lauterbur PC (1973) Image formation by induced local interactions. Examples employing nuclear magnetic resonance. Nature 242:190–191
Li Y, Tanaka T (1990) Kinetics of swelling and shrinking of gels. J Chem Phys 92:1365–1371
Maeda Y (2001) IR spectroscopic study on the hydration and the phase transition of poly(vinyl methyl ether) in water. Langmuir 17:1737–1742
Maeda Y, Mochiduki H, Yamamoto H, Nishimura Y, Ikeda I (2003) Effects of ions on two-step phase separation of poly(vinyl methyl ether) in water as studied by IR and Raman spectroscopy. Langmuir 19:10357–10360
Mark JE (1982) The use of model polymer networks to elucidate molecular aspects of rubberlike elasticity. Adv Polymer Sci 44:1–26
Onuki A (1993) Theory of phase transition in polymer gels. Adv Polymer Sci 109:63–121
Pelton R (2000) Temperature-sensitive aqueous microgels. Adv Colloid Interface Sci 85:1–33
Prior-Cabanillas A, Barrales-Rienda J, Frutos G, Quijada-Garrido I (2007) Swelling behaviour of hydrogels from methacrylic acid and poly(ethylene glycol) side chains by magnetic resonance imaging. Polym Int 56:506–511
Raasmark PJ, Andersson M, Lindgren J, Elvingson C (2005) Differences in binding of a cationic surfactant to cross-linked sodium poly(acrylate) and sodium poly(styrene sulfonate) studied by Raman spectroscopy. Langmuir 21:2761–2765
Richter S (2006) Contributions to the dynamical behavior of cross-linked and cross-linking systems: stimulus-sensitive microgels and hydrogels, reversible and irreversible gelation processes. Habilitation thesis, TU Dresden
Sahoo P, Rana P, Swain S (2006) Interpenetrating polymer network PVA/PAA hydrogels. Intern J of Polym Mater 55:65–78
Saiano F, Pitarresi G, Mandracchia D, Giammona G (2005) Bioadhesive properties of a polyaminoacidic hydrogel: Evaluation by ATR FT-IR spectroscopy. Macromol Bioscience 5: 653–661
Saito S, Konno M, Inomata H (1993) Volume phase transition of N-alkylacrylamide gels. Advanced Polymer Sci. 109:207–232
Schmidt T, Querner C, Arndt K-F (2003) Characterization methods for radiation cross-linked poly(vinyl methyl ether) hydrogels. Nucl Instr and Meth in Phys Res B 208:331–335
Shibayama M (1998) Spatial inhomogeneity and dynamic fluctuations of polymer gels. Macromol Chem Phys 199:1–30
Shibayama M (2006) Universality and specificity of polymer gels viewed by scattering methods. Bull Chem Soc Jpn 79:1799–1819
Shibayama M, Norisuye T (2002) Gel formation analyses by dynamic light scattering. Bull Chem Soc Jpn 75:641–659
Shibayama M, Morimoto M, Nomura S (1994) Phase separation induced mechanical transition of poly(N-isopropylacrylamide)/water isochore gels. Macromolecules 27:5060–5066
Shibayama M, Morimoto M, Nomura S (1994b) Phase separation induced mechanical transition of poly(N-isopropylacrylamide)/water isochore gel. Macromolecules 27:5060–5066
Smith AL (1979) Applied Infrared spectroscopy. Wiley, New York
Smith BC (1996) Fundamentals of Fourier Transform Infrared spectroscopy. CRC, New York
Smith BC (1999) Infrared Spectral Interpretation. CRC, London
Socrates G (2006) Infrared and Raman characteristic group frequencies. Wiley, West Sussex
Sorber J, Steiner G, Schulz V, Guenther M, Gerlach G, Salzer R, Arndt K-F (2008) Hydrogel-based piezoresistive pH sensors: investigations using FT- IR attenuated total reflection spectroscopic imaging. Anal Chem 80:2957–2962
Sotta P, Fülber C, Demco DE, Blümlich B, Spiess HW (1996) Effect of residual dipolar interactions on the NMR relaxation in cross-linked elastomers. Macromolecules 29:6222–6230
Suzuki M, Hirasa O (1993) An approach to artificial muscle using polymer gels formed by micro-phase separation. Adv Polym Sci 110:241–261
Tanaka T, Fillmore DJ (1979) Kinetics of swelling of gels. J Chem Phys 70:1214–1218
Tanaka T, Hocker LO, Benedek GB (1973) Spectrum of light scattered from a viscoelastic gel. J Chem Phys 59:5151–5159
Wall FT (1942) Statistical thermodynamics of rubber. J Chem Phys 10:132–134
Wall FT (1943) Statistical thermodynamics of rubber. III. J Chem Phys 11:527–530
Wall FT (1951) Statistical thermodynamics of rubber elasticity. J Chem Phys 19:1435–1439
Yan Q, Hoffman AS (1995) Synthesis of macroporous hydrogels with rapid swelling and deswelling properties for delivery of macromolecules. Polymer 36:887–889
Yoshida R, Uccida K, Kaneko Y, Sakai K, Kikuchi A, Sakurai Y, Okano T (1995) Comb-type grafted hydrogels with rapid deswelling response to temperature changes. Nature 374:240–242
Zerbi G (1999) Modern Polymer Spectroscopy. Wiley-VCH, Weinheim
Acknowledgments
The author thanks M. Knörgen (Martin-Luther-Universität Halle) for the fruitful cooperation on application of NMR imaging on smart hydrogels, and R. Reichelt (Westfälische Universität Münster) for the FESEM micrograph.
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Arndt, KF., Krahl, F., Richter, S., Steiner, G. (2009). Swelling-Related Processes in Hydrogels. In: Gerlach, G., Arndt, KF. (eds) Hydrogel Sensors and Actuators. Springer Series on Chemical Sensors and Biosensors, vol 6. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-75645-3_3
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