2 research outputs found
μ μ°©μ 리ννΈ λ°©λ²μΌλ‘ μ μλ λΉκ· μΌν λλ Έλ€κ³΅μ± λ§μ λ°λΌ νμ±λλ λλκ²½κ³μΈ΅μ λν μ°κ΅¬
νμλ
Όλ¬Έ(λ°μ¬) -- μμΈλνκ΅λνμ : 곡과λν μ κΈ°Β·μ 보곡νλΆ, 2022. 8. κΉμ±μ¬.λλ
Έμ±λμ λλ
Έμ±λμ λ
νΉν νΉμ±μΌλ‘ μΈν΄ λ§μ΄ν¬λ‘/λλ
Έμ 체 μμ€ν
μμ λ리 νμ©λμ΄ μλ€. λλ
Έμ±λμ λ
νΉν νΉμ± μ€ νλλ‘ μ κΈ° μ΄μ€μΈ΅μ κ²ΉμΉ¨μ μν΄ μ λλλ μ΄μ¨ μ νμ±μ΄ μλ€. μ΄μ¨ μ νμ±μ νμ©νμ¬, λλ
Έ μ±λμ μ¬μ©νλ μ κΈ°μλ ₯νμ μμ€ν
μ΄ λ€μνκ² κ°λ°λμ΄ μλ€. λ§μ΄ν¬λ‘/λλ
Έ μ 체 νλ«νΌμ νμ₯μ±κ³Ό κ°μμ±μ΄λΌλ μ₯μ μΌλ‘ μΈν΄, μ κΈ°μλ ₯ν μμ€ν
μ λν μ΄ν΄λ₯Ό μν μ°κ΅¬μ νμ©λμ΄ μλ€. λ°λΌμ λ§μ΄ν¬λ‘ μ₯μΉλ μ€μ μμ€ν
μ λͺ¨μ¬νκΈ° μν΄ μ€μ μμ€ν
μ νΉμ±μ λͺ¨λ°©νλ λμμΈμΌλ‘ μ μλμ΄ μλ€. νμ§λ§ λλ
Έμ±λ μ μ κΈ°μ μ νκ³λ‘ μΈν΄ μ₯μΉμ μ€κ³μ μ νμ΄ μμλ€. λ°λΌμ λ³Έ λ
Όλ¬Έμμλ λλ
Έλ€κ³΅μ±λ§ ν¨ν°λ λ°©λ²μ κ°λ°νκ³ ν΄λΉ ν¨ν°λ λ°©λ²μΌλ‘ μ μλ λ§μ΄ν¬λ‘/λλ
Έμ 체 νλ«νΌμ μ΄μ©νμ¬ νλ«νΌ λ΄μ λλ κ²½κ³μΈ΅μ μ‘°μ¬νμλ€.
λ¨Όμ μμμ λͺ¨μμ κ°μ§ λλ
Έλ€κ³΅μ± λ§μ μ μμ μν μ μ°©μ 리ννΈ λ°©μμ μ μνμλ€. ν΄λΉ λ°©μμ μ°μ νλΌμ¦λ§ μ²λ¦¬μ μ€ν μ½ν
μ νμ©νμ¬ κ· μΌνκ³ μ λ°ν λλ
Έλ€κ³΅μ± λ§μ ν¨ν°λμ΄ κ°λ₯νλ€. μ μ λ°©μμ μ ν¨μ±μ μ
μ¦νκΈ° μν΄, μ¬κ°ν, μ¬μΈν, ν±λν, μΌκ°ν, νλν ννμ λͺ¨μμ κ°μ§λ©°, 5 m, 15m, 150m μ λκ»λ₯Ό κ°μ§ λ§μ΄ν¬λ‘μ±λμ λ°λΌ ν¨ν°λ λ λλ
Έλ€κ³΅μ± λ§μ΄ μλ λ§μ΄ν¬λ‘/λλ
Έμ 체 νλ«νΌμ μ μνμλ€. ν¨ν°λμ μ νμ±μ μ΄μ¨ λλ λΆκ·Ήμ μΈ κ°μ§ λ©μ»€λμ¦ (νλ©΄ μ λ, μ κΈ°μΌν¬μ λ, μ κΈ°μΌν¬ λΆμμ )μ κ°μνλ₯Ό ν΅ν΄ νμΈνμλ€. λν, μ κΈ°μΌν¬μ λ μμκ³Ό μ κΈ°μΌν¬ λΆμμ μμμμμ κ΅΄κ³‘μ§ νλ©΄μ μ΄μ¨ λλ λΆκ·Ήμ λν μν₯μ μ°¨μ΄λ₯Ό μ§μ μ μΈ κ°μνμ μ κΈ°μ μΈ μΈ‘μ μ ν΅ν΄ νκ°νμλ€. λ°λΌμ μ μλ λλ
Έλ€κ³΅μ± λ§ μ μ λ°©μμ΄ μ€μ μμ€ν
κ³Ό μ μ¬ν λ§μ΄ν¬λ‘/λλ
Έ μ 체 νλ«νΌμ μ μμ κ°λ₯νκ² ν κ²μ΄λΌ κΈ°λνλ€.
λλ²μ§Έλ‘ μ΄μ¨ κ΅ν λ§μ 물리μ μμλ‘ νμ©λμ΄μ¨ κ°ν ꡬ쑰λ₯Ό νμ©ν μ κΈ°μλ₯μ μ λ ¬μ λν΄ μ
μ¦νμλ€. μ€ν μ₯μΉλ μ μ°©μ 리ννΈ λ°©μμ νμ©νμ¬ μ μνμλ€. μμ μ μΈ μ κΈ°μλ₯λ κ°ν 체μ νμ΄ λκ³ μ΄μ¨κ³΅νμΈ΅κ³Ό κ°κΉμΈ λ μ λ ¬λλ€λ κ²μ μ μ° λͺ¨μ¬μ μ€νμ ν΅ν΄ νμΈνμμΌλ©°, μλ₯ μ λ ¬μ μν κ°ν체μ κΈ°ννμ 쑰건μ νμΈνμλ€. λν κ°ν체λ₯Ό μ΄μ©ν΄ νΌλ μμμμλ μ κΈ° μλ₯λ₯Ό μ λ ¬νμλ€. μ κΈ° μλ₯λ μ λ ¬λ‘ μΈν΄ μμ νλμμΌλ©°, ν΄λΉ μμ νλ μκ°μΌλ‘ νκ· ν μμ΄μ¨ λλ λΆν¬(μ μ° λͺ¨μ¬) λ° νκ΄ μΈκΈ° λΆν¬(μ€ν)μ ν΅ν΄ μμΉννμλ€. λ, μ λ₯ λν λλ
Έλ€κ³΅μ± λ§ λ΄μ κ°ν체λ₯Ό ν΅ν΄ μμ νλμμμ μ
μ¦νμλ€. λ°λΌμ κ°νμ²΄κ° λ€μν λλ λΆκ·Ή μμ€ν
λ΄μ μ κΈ° μλ₯μ μμ νμ νμ©λ μ μμμ μ μνλ€.
λ§μ§λ§μΌλ‘ μ΄μ¨ κ΅νμΌλ‘ μΈν νμ°μλμ κΈ°λ°μΌλ‘ ν μ°μμ μ΄κ³ μλ°μ μΈ λλ
Έμ
μ λΆλ¦¬ μ₯μΉλ₯Ό μ μνμλ€. νμ°μλ κΈ°λ°μ λΆλ¦¬ μ₯μΉλ μ μ°©μ 리ννΈ λ°©μμ νμ©νμ¬ μ μνμλ€. λΆλ¦¬ μ₯μΉ λ΄μ λ°°μ 거리μ λν κ²½ν₯μ±μ κΈ°μ‘΄μ μλ°μ νμ°μλ κΈ°λ°μ μμ€ν
μ κ²½ν₯μ±μ λ°λλ€. λ°λΌμ ν¬κΈ°μ μ°¨μ΄(40 nm, 200 nm, 2 m)λ‘ μΈν νμ°μλμ μ΄λλλ₯Ό λ νν°ν΄μ λΆλ¦¬νλ κ²μ΄ κ°λ₯νλ€. λν Tris λ²νΌ μ©μ‘μ μΆκ°λ₯Ό ν΅ν΄ μ΄μ¨ λλ ꡬ배λ₯Ό ν₯μμμΌ λΆλ¦¬ ν¨μ¨μ μ¦κ°μμΌ°λ€. Trisλ₯Ό μΆκ°λ λΆλ¦¬λ λ²νΌ μ©μ‘μ΄ pHμ λ―Όκ°ν μ체 λΆμμ μ ν©νλλ‘ νλ μν λ νλ€. λ°λΌμ μ μλ μ°μμ μ΄κ³ μλ°μ μΈ νμ°μλ κΈ°λ°μ λΆλ¦¬ νλ«νΌμ΄ λ€μν λλ
Έ μ체 λΆμμ λΆμμ νμ©λ μ μμμ κΈ°λνλ€.Nanochannels have been widely utilized in micro/nanofluidic systems due to the unique characteristics of the nanochannels. One of the most unique characteristics is ion selectivity induced by the overlap of electrical double layer. Using ion selectivity, electrokinetic systems employing nanochannels have been widely developed. Due to the scalability and visibility, micro/nanofluidic platforms have been utilized for the fundamental studies of the electrokinetic systems. To simulate the realistic macro systems, the micro platforms have been fabricated with a design which mimics the systems. However, the designs of the platforms have been limited due to the limitations in the nanojunction fabrication methods. Therefore, in this thesis, a nanoporous membrane patterning method was developed and concentration boundary layers were investigated with micro/nanofluidic platforms fabricated with the patterning method.
First, an arbitrary-shaped nanoporous membrane fabrication with adhesive lift method was presented. The presented method utilizes oxygen plasma treatment and spin coating for the uniform and precise patterning of the nanoporous membrane. To demonstrate the fabrication method, we fabricated micro/nanofluidic platforms with membranes patterned along microchannels with surface shape of square, sine, sawtooth, triangle and fractal wave and with depth of 5 m, 15 m and 150 m. The conformal patterning was confirmed by direct visualization of ion concentration polarization in three mechanisms (surface conduction, electroosmotic flow and electroosmotic instability). Furthermore, the different effect of undulated surface on ion concentration polarization in electroosmotic flow regime and electroosmotic instability regime was evaluated with direct visualization and electric measurements. Therefore, we suggest that the presented nanoporous membrane fabrication method would enable the fabrication of near-practical micro/nanofluidic platforms.
Secondly, we demonstrated the alignment of electroconvection utilizing reinforcing structures which have been utilized as physical component of ion selective membrane. The experimental devices were fabricated with the adhesive lift method. Through numerical simulation and experiments, we confirmed that the stable electroconvection was aligned with reinforcements which was wide in width and close to ion depletion zone, and the geometric conditions of reinforcements for the stable vortex alignment was confirmed. Furthermore, the electroconvection in chaotic regime was also aligned with reinforcing structures. Due to the alignment, the chaotic electroconvection was stabilized and the stabilization was quantified with time-averaged profiles of cation concentration (simulation) and fluorescence intensity (experiment). Moreover, we demonstrated that the electric current was stabilized with the reinforcing structures inside the ion selective membranes. Thus, we present that the reinforcing structures would be utilized for the stabilization of electroconvection in various concentration polarization systems.
Finally, we presented a continuous and spontaneous nanoparticle separator based on diffusiophoresis induced by ion exchange. The diffusiophoretic separator was fabricated with the adhesive lift method. In the separator, the exclusion distance followed the scaling law of the conventional spontaneous diffusiophoretic system. Thus, we separated particles with different diffusiophoretic mobility due to the difference of size (40 nm, 200 nm and 2 m). Furthermore, the separation resolution was increased by enhanced concentration gradient induced by addition of Tris buffer. The addition of Tris also played a role as a pH regulator so that the separated buffer stream can be appropriate for pH-sensitive biomolecules. Therefore, we expect the presented continuous and spontaneous diffusiophoretic separation platform to be utilized for analysis of various nanoscale biomolecules.Chapter 1. Introduction 1
1.1. Ion-selectiviy of a Nanochannel 1
1.2. Ion Concentration Polarization 4
1.2.1. Mechanisms of Overlimiting Conductance 6
1.2.2 Electroconvection 9
1.3. Diffusiophoresis 11
Chapter 2. Adhesive Lift Method for Patterning Arbitrary-shaped Thin Ion-selective Films in Micro/nanofluidic Device 13
2.1. Introduction 13
2.2. Methods 18
2.2.1. Fabrication of Micro/Nanofluidic Device with Arbitrary-shaped Membrane 18
2.2.2. Chemicals and Experimental Setup 26
2.3. Results and Discussion 28
2.3.1. Arbitrary-shaped Nanoporous Membrane along the Main Channel 28
2.3.2. An IDZ along Arbitrary-Shaped Membrane 30
2.3.3. Near-practical Electro-desalination Platform using the Arbitrary-shaped Membrane 36
2.3.3.1. Device Configuration 36
2.3.3.2. Direct Visualization of IDZ in Near-practical Electro-desalination Platform 40
2.3.3.3. Overlimiting Conductance in EOI and EOF Regime 43
2.4. Conclusions 47
Chapter 3. Non-negligible Effects of Reinforcing Structures inside Ion Exchange Membrane on Stabilization of Electroconvective Vortices 49
3.1. Introduction 49
3.2. Methods 54
3.2.1. Numerical Methods 54
3.2.2. Experimental Methods 60
3.3. Results and Discussion 64
3.3.1. Demonstration of Electric Field Focusing due to Reinforcing Structure 64
3.3.2. Demonstration of EC Alignment depending on Geometry of Reinforcing Structure 67
3.3.3. Alignment of EC by Reinforcing Structures in Chaotic Regime 78
3.3.4. Stabilization of Electric Current using Reinforcing Structures in Chaotic Regime 83
3.4. Conclusions 89
Chapter 4. Continuous and Spontaneous Nanoparticle Separation by Diffusiophoresis 91
4.1. Introduction 91
4.2. Materials and Methods 94
4.2.1. Fabrication of Diffusiophoretic Separation Device 94
4.2.2. Chemical Preparation 95
4.2.3. Experimental Setups 95
4.3. Results and Discussion 96
4.3.1. Concept of Diffusiophoretic Separation 96
4.3.2. Diffusiophoretic Exclusion near Ion-exchange Medium 99
4.3.3. Continuous Separation of Nano-sized Colloidal Suspensions 104
4.3.4. Separation Efficiency Improvement by Enhanced Concentration Gradient 107
4.4. Conclusions 111
Chapter 5. Concluding Remarks 112
Appendix 114
A. Numerical Modeling of Concentration Boundary Layer near the Ion-selective Membrane with Water Absorption 114
A.1. Numerical Methods 114
A.1.1. 2D Numerical Model for Diffusiophoretic Separation 114
A.1.2. 1D Numerical Model for Concentration Boundary Layer with Tris Buffer 117
A.2. Results and Discussions 120
A.2.1. Taylor Dispersion of the Nanoparticle Suspensions 120
A.2.2. Numerical Results of Ion Concentration with Injection of Tris 125
Bibliography 128
Abstract in Korean 139λ°