CMOS Capacitive Sensors for Lab-on-Chip Applications: A Multidisciplinary Approach (Analog Circuits and Signal Processing)

✍ Scribed by Ebrahim Ghafar-Zadeh, Mohamad Sawan

• Publisher: Springer
• Year: 2010
• Tongue: English
• Leaves: 154
• Category: Library

✦ Synopsis

1.1 Overview of Lab-on-Chip Laboratory-on-Chip (LoC) is a multidisciplinary approach used for the miniaturization, integration and automation of biological assays or procedures in analytical chemistry [1–3]. Biology and chemistry are experimental sciences that are continuing to evolve and develop new protocols. Each protocol offers step-by-step laboratory instructions, lists of the necessary equipments and required biological and/or chemical substances [4–7]. A biological or chemical laboratory contains various pieces of equipment used for performing such protocols and, as shown in Fig. 1.1, the engineering aspect of LoC design is aiming to embed all these components in a single chip for single-purpose applications. 1.1.1 Main Objectives of LoC Systems Several clear advantages of this technology over conventional approaches, including portability, full automation, ease of operation, low sample consumption and fast assays time, make LoC suitable for many applications including. 1.1.1.1 Highly Throughput Screening To conduct an experiment, a researcher fills a well with the required biological or chemical analytes and keeps the sample in an incubator for some time to allowing the sample to react properly. Afterwards, any changes can be observed using a microscope. In order to quickly conduct millions of biochemical or pharmacolo- cal tests, the researchers will require an automated highly throughput screening (HTS) [8], comprised of a large array of wells, liquid handling devices (e.g., mic- channel, micropump and microvalves [9–11]), a fully controllable incubator and an integrated sensor array, along with the appropriate readout system.

✦ Table of Contents

CMOS Capacitive Sensors for Lab-on-Chip Applications
Abbreviations
Chapter 1
Introduction
1.1 Overview of Lab-on-Chip
1.1.1 Main Objectives of LoC Systems
1.1.1.1 Highly Throughput Screening
1.1.1.2 Early Detection of Disease
1.1.1.3 Point-of-Care (PoC) Testing
1.1.1.4 Environmental Assessment
1.2 From Macro to Micro Bioassays
1.2.1 Micro-scale Liquid Handling
1.2.2 Thermal Management in Microenvironment
1.2.3 DNA Amplification
1.2.4 Sample Handling
1.2.5 Advantages of Performing Bioassays in Microscale
1.3 CMOS-Based LoC
1.3.1 Manipulation Methods
1.3.2 Optical Techniques
1.3.3 Electrochemical Sensors
1.3.4 Mechanical Sensors
1.3.5 Magnetic Sensor
1.3.6 Temperature Control
1.3.7 Capacitive Sensing LoC
1.4 Objectives and Organization of Book
Chapter 2
Capacitive Sensing Electrodes
2.1 On-Chip Microelectrode Configurations
2.1.1 Passivated Electrodes
2.1.2 Unpassivated Electrodes
2.1.3 Sensitivity-Enhanced Passivated Electrodes
2.1.4 Quasi Interdigitated Electrodes
2.1.5 Gold Electrodes on CMOS Chip
2.1.6 Microfluidic Channel Integrated Atop Sensing Electrodes
2.2 Micromachining Gold Electrode on CMOS Chip
2.3 Electrical Model of Sensing Electrodes
2.4 Summary
Chapter 3
Capacitive Bio-interfaces
3.1 Biochemical Capacitive Sensing Methods
3.1.1 Hybridization Detection
3.1.2 Antibody–Antigen Recognition
3.1.3 Living Cells Monitoring
3.1.4 Organic Solvent Sensors
3.1.5 Bacteria Growth Monitoring
3.1.6 Polyelectrolyte Monolayer
3.1.7 Detection of Protein Conformation
3.2 Design of Recognition Element: An Example for Continuous Glucose Monitoring
3.2.1 Introduction to Glucokinase-Based Glucose Sensor
3.2.2 Immobilization of Glucokinase on Gold Electrode
3.2.3 Glucose Testing
3.3 Summary
Chapter 4
Capacitive Interface Circuits for LoC Applications
4.1 LBCS Versus MBCS
4.1.1 Instant Measurement
4.1.2 Aqueous Measurement
4.1.3 On-Chip Sensing Electrodes
4.1.4 Measurement Time
4.1.5 RC Model Sample
4.2 LBCS Methods
4.2.1 SC-Based Interface Circuit
4.2.2 Time Constant Method
4.2.3 Capacitive Inverter Amplifier
4.2.4 CBCM Methods
4.3 Core–CBCM Interface Circuit
4.3.1 Principle of CBCM for Sensing Applications
4.3.2 Two Transistors CBCM Sensor
4.3.3 Opamp-Based Integrator Incorporated with CBCM Sensor
4.3.4 Differential Current CBCM Techniques
4.3.5 Current Mirror Integrated with CBCM Structure
4.3.5.1 Differential Voltage Technique
4.3.5.2 Differential Current Technique
Ionic Conductive Solutions
Differential Capacitive Sensor
Sensor Characteristics
Linearity
Integrating Capacitor
Geometrical Issues of Transistors
Thermal Issues
Calibration Technique
Off-Chip Resistive Technique
Adjustable Current Gain
Further Modification
Practical Considerations
4.4 Core-CBCM SD Capacitive Sensor
4.4.1 Definitions
4.4.2 Charge to Digital Converter
4.4.3 Discussions
4.4.4 Circuit Level Simulation Results
4.4.5 Decoding Technique
4.4.5.1 Simple Decoding Method
4.4.5.2 Optimum Decoding Methods
4.5 Core-CBCM Capacitive Sensing System
4.5.1 A System Level Realization
4.5.2 Experimental Procedures
4.6 Summary
Chapter 5
Microfluidic Packaging Process
5.1 Microfluidic Packaging Methods
5.1.1 On-Chip Micromachining Procedures
5.1.2 Adhesive Methods
5.1.2.1 Advantages and Disadvantages
5.1.3 Rapid Prototyping Techniques
5.2 Direct-Write Microfabrication Process
5.2.1 Direct-Ink Writing
5.2.2 Fundamentals of DWFP
5.2.3 Direct-Write Microfluidic Fabrication Process
5.2.3.1 Procedures
5.2.3.2 Fabrication Set-Up
5.2.3.3 Advantages and Disadvantages of DWFP
5.2.3.4 Other Practical Considerations of DWFP
Dispensing Model
Micro-nozzle
Micofluidic Fitting
Substrate for DWFP
Microfluidic Structure
Degassing
5.3 Direct-Write Microfluidic Packaging Procedure
5.3.1 Encapsulation of Bonding Pads and Wires
5.3.2 Ink Deposition
5.3.3 Fitting Connections
5.3.4 Fugitive Dam
5.3.5 Ink Encapsulation and Filling Process
5.3.6 Ink Removal and Analyte Injection
5.4 Emerging Applications of DWFP
5.4.1 Microvalve
5.4.2 Direct-Write Heat Exchanger
5.4.3 Optical Waveguide for Biosensing Applications
5.5 Summary
Chapter 6
Current Technology and Future Works
6.1 Conventional Impedometric and Capacitive Measurement Systems
6.2 Handheld Impedance Measurement Systems
6.3 Towards Fully Integrated Capacitive Sensing LoC
6.3.1 Packaging
6.3.2 Capacitance Characterization
6.3.3 Electrical Modeling of Biological Sample
6.3.3.1 Generic Microelectronic Circuitry
6.3.4 Cleaning Procedure
6.4 Summary
References