Biosensing with Silicon: Fabrication and Miniaturization of Electrochemical and Cantilever Sensors (SpringerBriefs in Materials)

This book discusses two silicon biosensors: an electrochemical sensor – the Electrolyte Insulator Silicon Capacitor (EISCAP), and a mechanical resonant cantilever sensor. The author presents the principle and the technology behind the device fabrication and miniaturization, stable and reproducible functionalization protocols for bioreceptor immobilization, and the measurement and the data analysis for extracting the best performance from these sensors. EISCAP sensors, used for the estimation of triglycerides and urea, have been improved through the use of micromachining processes. The miniaturization brought out advantages as well as challenges which are discussed in this book, resulting in a prototype mini-EISCAP with a readout circuit for fast and accurate estimation of triglycerides. The author also reports on the sensitivity improvements in the estimation of triglycerides and urea obtained with the polycrystalline silicon cantilever and its measurements in liquid media. The book is ideal for materials scientists and engineers working in the field of biosensors and MicroElectroMechanical systems (MEMS) and their optimizations, as well as researchers with biochemical or biomedical expertise, in order to have a fresh and updated review on the last progresses reached with EISCAPs and cantilever sensors. Preface Acknowledgements Contents 1 Introduction 1.1 Biosensor 1.2 Silicon Biosensors 1.3 Electrochemical Biosensors 1.4 Microcantilever Biosensors 1.5 Triglyceride Sensors 1.6 Urea Sensor References 2 Technology/Nuts and Bolts 2.1 Unit Processes 2.1.1 Oxidation 2.1.2 Doping 2.1.3 Lithography 2.1.4 Chemical Vapour Deposition (CVD) Processes 2.1.5 Etching Wet/Dry 2.1.6 Silicon Wet Etching 2.2 Micromachining 2.3 Characterisation 2.4 Surface Functionalization References 3 Electrolyte Insulator Semiconductor Capacitor (EISCAP) Biosensor 3.1 Principle of Operation 3.2 Fabrication of Sensors 3.3 Calibration and Measurements 3.4 Biosensor 3.4.1 Triglyceride Sensor 3.4.2 Triglyceride Estimation in Blood Serum 3.5 Urea Sensor 3.5.1 Measurement of Urea in Blood Serum 3.5.2 Measurement of Urea in Milk 3.6 Miniaturised EISCAP 3.6.1 Optimisation of Mini-EISCAPs 3.7 Mini-EISCAP Triglyceride (TG) Sensor 3.8 Summary References 4 Readout Circuit and Measurement Protocol for Mini-EISCAPs 4.1 Principle of Flat-Band Voltage Measurement 4.2 Measurement of pH 4.3 System-On-Chip Implementation 4.3.1 Measurement of pH 4.4 Readout Protocol for Estimating TG with EISCAP 4.5 Measurement of TG with Mini-EISCAP References 5 Cantilever Sensors for Triglycerides and Urea 5.1 Cantilevers as Sensors 5.2 Sensing Methods 5.3 Detection of Triglycerides (TG) Using Microcantilevers 5.4 Sensitivity and Reliability for Measurements in Liquids 5.4.1 Frequency Sweep and Spurious Modes 5.4.2 PLL Tracking 5.5 Improving the Sensitivity 5.5.1 Fabrication of Thin Polysilicon Cantilevers 5.6 Detection of Triglycerides Using LDV 5.7 Urea Sensor 5.8 Conclusion References 6 Conclusion References