MEMS Final

Scaling Laws

Address the structural and functional consequences of size changes among similar structures or organisms.

MEMS Materials

Include silicon (single crystal, polycrystalline), metals (aluminum, copper, gold, titanium, platinum), and insulators (silicon dioxide, silicon nitride, titanium nitride).

Intrinsic Conductivity

Increasing temperature leads to the production of free carriers in semiconductors through N-type and P-type doping.

Transistors

Devices that switch and amplify signals, crucial in integrated circuits, including bipolar junction transistors and field-effect transistors.

Moore’s Law

States that the number of transistors on a chip doubles approximately every two years.

Microfabrication Processes

Involve property modification, patterning, subtractive processes like etching, and additive processes such as oxidation and deposition.

Polymer MEMS

Utilize materials like elastomers (PDMS), thermoplastics (PMMA, PC, PS), hydrogels, and biodegradable polymers in microfabrication.

Soft Lithography

A set of fabrication methods based on using a patterned elastomer layer like PDMS, including microcontact printing and replica molding.

Glass MEMS

Utilize glass materials for applications like DNA microarrays and point-of-care diagnostics, involving photolithography and etching processes.

Carbon MEMS

Involve the patterning and pyrolysis of photoresists to yield carbon films and 3D microstructures for applications like batteries and sensors.

Micromixers

Mixing is crucial in microfluidics for homogenization of solutions in chemical reactions and biological processes like cell activation and protein folding.

Passive

Micromixers with no moving parts relying on diffusion and geometry for mixing, including T and Y mixers, sequential mixing, and throttle design.

Active

Micromixers enhancing fluid mixing by increasing interfacial area through piezoelectric devices, electrokinetic mixers, or chaotic convection.

Serpentine Mixer

Micromixer design with two PDMS layers creating a helical flow pattern.

Passive Chaotic Mixer

Micromixer utilizing microridges to induce turbulent flow at low Reynolds numbers.

Sensor

Device converting physical parameters into electrical signals for detection, with applications in various fields.

MEMS in Sensor Technology

Miniaturization, multiplicity, and integration of microelectronics for sensor control and operation.

Sensor Classifications

Categorized into biological, chemical, mechanical, thermal, electrical, magnetic, and radiation sensors.

Biosensor

Device combining biological elements with transducers to produce detectable electrical signals.

Biological Element

Component in biosensors binding target molecules, requiring specificity, stability, and immobilization.

Physiochemical Transducer

Part of biosensors transforming signals from bioelements into measurable electrical outputs, classified into various types.

Enzyme-Based Biosensors

Biosensors utilizing enzymes for simple design and operation in detecting specific substrates.

Antibody-Based Biosensors

Biosensors, also known as immunosensors, offering high specificity and sensitivity using antibodies for detection.

Micromosaic Immunoassay

Microfluidic technique controlling antigen immobilization and antibody flow, producing fluorescence mosaic images.

Cell-Based Biosensor

Biosensor detecting cellular parameters, pharmaceutical effects, and environmental toxicity.

Immobilization of Biological Elements

Methods like physical absorption, entrapment, and covalent attachment connecting bioelements to transducers.

Transducing Mechanism

Techniques like electrochemical, optical, mechanical sensing converting bioelement interactions into measurable signals.

Optical Biosensors

Biosensors linking changes in light intensity to mass or concentration variations, utilizing fluorescent or colorimetric molecules.

Genomics

Study of DNA mechanisms, protein synthesis, gene expression, and genetic material exchange, aided by techniques like PCR and DNA sequencing.

RNA Types

Messenger, transfer, and ribosomal RNA involved in transcription and protein synthesis processes.

Piezoelectric effect

Electric charge generated in response to mechanical stress

Biosensing with piezoelectric materials

Utilizing materials like quartz crystals for biosensing applications

Actuation using piezoelectric materials

Conversion of electrical energy into precise mechanical motion

P-N junction function

Dissipating power and generating heat

Polymer for injection molding

PMMA

Three molding processes

Hot embossing, compression molding, injection molding

Moore’s Law

States that the number of transistors in a dense integrated circuit doubles every two years

Silicon as a semiconductor

Its conductivity can be tailored by doping

Integrated circuit components

Active components include diodes, passive components include resistors

Commonly used materials in BioMEMS devices

Silicon, glass, polymer

Microfabrication processes for silicon-based MEMS

Deposition, patterning, etching

Glasses for MEMS fabrication

Pyrex and quartz

Glass micromachining process

Powder blasting

MEMS

Microelectromechanical system

IC

Integrated circuit

PVD

Physical vapor deposition

CVD

Chemical vapor deposition

PDMS

Polydimethylsioxane

PC

Polycarbonate

Advantages of using MEMS device for ELISA

Faster and more sensitive detection, less reagent used

Electrostatic force in smaller devices

Used due to l² relationship, less affected by scale changes

Positive photoresist result

Unexposed resist remains

Negative photoresist result

Exposed resist remains

Process for creating a shallow rectangular trench in pyrex

Powder blasting

applications of MEMS devices

drug delivery, DNA microarray, lab on a chip, neural probe

<l² means __________ effect at smaller sizes

reduced

>l² means _________ effect at smaller sizes

increased

MEMS processes

lithography, etching, deposition, packaging

small amount of Si replaced with group V element, extra electron for each atom replaced

N-type doping

small amount of Si replaced with group III element, hole created for each atom replaced

P-type doping

dopant concentration is 5 to 6 orders of magnitude higher concentrations than intrinsic

extrinsic semiconductors

when electrons and holes recombine, energy is released in the form of photons

eletroluminescence