Lecture 9 Fundamentals of Multiscale Fabrication Applications I: (Bio)MicroElectroMechanical Systems Kahp-Yang Suh Associate Professor SNU MAE sky4u@snu.ac.kr

Applications of multiscale systems Multifunctional nanomaterials (particles, tubes, composites,…) Synthesis is now highly advanced Integration issues are yet to be solved (Bio)Microelectromechanical systems Sensors/actuators: micro/nanoscale Detection/measurement: meso/macroscale Biomimetic multiscale structures Many length scales and hierarchy Adapted to each function and mechanism Micro- and Nanofluidics Surface/interfacial effects are dominant Fabrication is still challenging Photonic and energy devices Efficiency is limited by defects and many interfaces Material issues are getting more important

► Multiscale structures for various applications Biomimetic surfaces Photonic devices Nature Nanotechnology, 2007 Langmuir, 2006 Electronic devices Micro/nanofluidics APL, 1999 SCIENCE, 2000

What are microelectromechanical systems (MEMS)? The term MEMS refers to a collection of microsensors and actuators which can sense its environment and have the ability to react to changes in that environment with the use of a microcircuit control. They include, in addition to the conventional microelectronics packaging, integrating antenna structures for command signals into micro electromechanical structures for desired sensing and actuating functions. The system also may need micropower supply, micro relay and microsignal processing units. Microcomponents make the system faster, more reliable, cheaper and capable of incorporating more complex functions. cf) Human body ex) RF-MEMS: MEMS for RF integrated circuits BioMEMS: Biological sensing or actuation Micro-opto-electromechanical systems (MOEMS) Micro total analysis systems (TAS)

‘Miniaturization engineering’ is a more appropriate name than MEMS, but the name MEMS is more popular. It involves a good understanding of scaling laws, manufacturing methods and materials. Initially it involved mostly Si and mechanical sensors (e.g., pressure, acceleration, etc). Miniaturization engineering or MEMS (NEMS) applied to biotechnology is called BIOMEMS (BIONEMS). From MEMS to BioMEMS MEMS: MicroElectroMechanical Systems NEMS: NanoElectroMechanical Systems

Device fabrication A material to create the device – Silicon, Glass, Polymer, Metal… A process to follow – Micromachining, Nanofabrication… Process characteristics - Reproducible - Scalable - Inexpensive - Environmentally friendly Tools to create the device – Lithography, Bonding… Tools to examine and verify the device – Microscopy, Electrical analysis … Packing Integration methods and tools

MEMS: Smart Systems Microsystems or MEMS System Techniques Integrateable Sensors Integrateable Actuators Process Engineering Medical Technology Automotive Technology Security & Environmental Household & Office Tech. Microsystems or MEMS Micro Techniques Materials & Effects Signal Processing Components

Microelectronics vs. MEMS Microsystems (Silicon-based MEMS) Uses single crystal silicon die, silicon compound, and plastics Single crystal silicon die, GaAs, quarts, polymers, metals Transmits electricity for specific electrical functions Performs biological, chemical, electromechanical functions Stationary structures May involve moving components Primary 2-D structures Complex 3-D structures Complex patterns with high density over substrates Simpler patterns over substrates Fewer components in assembly Many components to be assembled IC die is completely protected from contacting media Sensor die is interfaced with contacting media Matured IC design methodology Lack of engineering design methodology and standards Large number of electrical feedthroughs and leads Fewer electrical feedthroughs and leads Industrial standards available No industrial standards to follow Mass productions Batch production or on customer-needs basis Fabrication techniques are proved and well documented Many microelectronics fabrication techniques used Manufacturing techniques are proved and well documented District manufacturing techniques Packaging technology is relatively well established Packaging technology is at the infant stage

What can MEMS do?

What else can MEMS do?

Digital Light Processingtm (TI DMD, 1987) Microfabricated digital mirror High-Brightness (vs. LCD) High-Resolution

ADXL Accelerometer Electro Mechanical System On Chip Compact High Performance (linearity, sensitivity) Low cost

Automotive Applications Navigation Gyroscope Air bag XL Silicon Nozzles Tire pressure sensor

Aerospace Applications

Industrial Applications

Customer…

MEMS vs. BIOMEMS

Definition of BioMEMS From a systemic aspect: From a component aspect: BioMEMS usually contains sensors, actuators, mechanical structures and electronics. Such systems are being developed as diagnostic and analytical devices. - Suzanne Berry, TRENDS in Biotechnology (2002) From a component aspect: BioMEMS is the research of microfabricated devices for biological applications. - Tejal A. Desai, Biomolecular Engineering (2000) MEMS technology is an engineering solution for biomedical problems. Bio-chip can be used for diagnosis, treatment, substituting insertion.

Drug Delivery Microneedles

Biomedical…

Drug Delivery Platforms

MEMS Microblades Here is the system layout of Prof Goodson’s project. We can see that the whole system was on one chip and there are several important components like the macro scale heat exchanger system. They are Micro channels in the evaporator region which sits on the chip, heat source; Condenser region and electrokinetic pump providing the driving force of the fluidic medium. Let’s talk about the EK pump first. EK pump controls flow by electrical potential across a porous medium, which generates a force that induces the liquid to flow. The electroosmotic flow (EOF) is generated in the charge double layer that forms in the first few nanometers of the liquid/dielectric interface. Solvated ions move under the influence of an applied external field, carrying the bulk liquid by viscous drag. The electroosmotically-driven flow rate, QEOF, is directly proportional to the applied voltage and the zeta potential of the porous pump medium. The maximum pressure generated, PMAX, is inversely proportional to the square of the pump medium's pore diameter. Therefore, by optimizing the pump medium's pore size and zeta potential, and controlling the applied voltage. There is a company from Sandia lab research group focus on EK pump application. The animation can help us understand the physical phenomena behind that.

Why biochip? - Big bang of bio information

What is biochip? Devices which allow super-high-speed, high-sensitive analysis of biologically active DNA, Protein, Cells that are highly integrated on glass, silicon or polymer substrates.

Types of biochip Micro array chip Biochip LOC Bio sensor Bio

DNA chip - functional genomics Chip which allows to check gene expression or mutation by adhering highly integrated Oligonucleotide, cDNA, genomic DNA, etc. on its substrate

Protein chip - proteomics Chip that has ligands and proteins those can react with specific protein on its surface Proteins could be segregated, checked and quantitatively analyzed on the chip

Cell Chip - functional cellulomics Detection of physiological signal by real-time reaction of live cells which was impossible by existing methods

Lab on a Chip Micro fab. techniques, Micro/nano fluidics techniques are applied Dilution, mixing, reaction, separation of sample could be accomplished on a chip

Advantages and Applications of LOC

Lab-On-A-Chip Applications to Genomics & Proteomics

Applications & Vision Chips for research for diagnosis various platform → various data gathering data researcher’s choice by market for diagnosis various products → same result reliability, sensitivity, accuracy are needed restricted by law and regulations Most chips were for research so far

Roadmap of Bio-chip Technique