28-11-2012, 05:35 PM
BIOMEDICAL APPLICATIONS OF MEMS
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Abstract
Micromachining and MEMS technologies can be used to produce complex electrical, mechanical,
fluidic, thermal, optical, and magnetic structures, devices, and systems on a scale ranging from
organs to subcellular organelles. This miniaturization ability has enabled MEMS to be applied in
many areas of biology, medicine, and biomedical engineering – a field generally referred to as
BioMEMS. The future looks bright for BioMEMS to realize (1) microsensor arrays that act as an
electronic nose or tongue, (2) microfabricated neural systems capable of controlling motor or
sensory prosthetic devices, (3) painless microsurgical tools, and (4) complete microfluidic systems
for total chemical or genetic analyses. In this paper we focused on micro fabrication,surface micro
machining, bulk micro machining, substrate bonding, non silicon fabrication and we also focused on
micro sensors like impedance sensors, polymer based sensors, electro chemical sensors, molecular
specific sensors, resonant sensors, cell based sensors and we also discussed like micro manipulators,
surgical micro instruments, micro pumps, micro valves, micro needle, micro filters, micro valves and
then finally we concluded after mentioning some micro systems useful for different analysis.
INTRODUCTION:
Microelectromechanical systems (MEMS) is a technology of miniaturization that has been largely
adopted from the integrated circuit (IC) industry and applied to the miniaturization of all systems
(i.e., not only electrical systems but also mechanical, optical, fluidic, magnetic, etc).
Miniaturization is accomplished with microfabrication processes, such as micromachining, that
typically use lithography, although other non-lithographic precision microfabrication techniques
exist (FIB, EDM, laser machining). Due to the enormous breadth and diversity of the field of
MEMS, the acronym is not a particularly apt one. However, it is used almost universally to refer to
the entire field (i.e., all devices produced by micromachining). Other names for this general field
include “microsystems”, popular in Europe, and “micromachines”, popular in Asia.
MICROFABRICATION:
Although many of the microfabrication techniques and materials used to produce MEMS have
been borrowed from the IC industry, the field of MEMS has also driven the development and
refinement of other microfabrication processes and non-traditional materials.
Conventional IC Processes and Materials:
photolithography; thermal oxidation; dopant diffusion; ion implantation; LPCVD; PECVD;
evaporation; sputtering; wet etching; plasma etching; reactive-ion etching; ion milling - silicon;
silicon dioxide; silicon nitride; aluminum Additional Processes and Materials used in MEMS:
anisotropic wet etching of single-crystal silicon;deep reactive-ion etching or DRIE; x-ray
lithography; electroplating; low-stress LPCVD films; thick-film resist (SU-8); spin casting;
micromolding; batch microassembly
piezoelectric films such as PZT; magnetic films such as Ni, Fe, Co,
and rare earth alloys; high
temperature materials such as SiC and ceramics; mechanically robust aluminum alloys; stainless
steel; platinum; gold; sheet glass; plastics such as PVC and PDMS
The methods used to integrate multiple patterned materials together to fabricate a completed
MEMS device are just as important as the individual processes and materials themselves. The two
most general methods of MEMS integration are described in the next two sub-sections: surface
micromachining and bulk micromachining.
Substrate Bonding:
Silicon, glass, metal and polymeric substrates can be bonded together through a variety of
processes (i.e.,fusion bonding, anodic bonding, eutectic bonding, and adhesive bonding). Typically
at least one of the bonded substrates has been previously micromachined. Substrate bonding is
typically done to achieve a structure that is difficult to form otherwise (i.e., large cavities that may
be hermetically sealed or a complex system of enclosed channels) or simply to add mechanical
support and protection.
Plastic Molding with PDMS:
Polydimethylsiloxane (PDMS) is a transparent elastomer that can be poured over a mold (e.g., a
wafer with a pattern of tall SU-8 structures), polymerized, and then removed simply by peeling it
off of the mold substrate. The advantages of this process include
(1) many inexpensive PDMS parts can be fabricated from a single mold,
(2) the PDMS will faithfully reproduce even sub-micron features in the mold,
(3) PDMS is biocompatible and thus can be used in a variety of BioMEMS applications, and
(4) since PDMS is transparent, tissues, cells, and other materials can be easily imaged through it.
Common uses of PDMS in biomedical applications include: microstamping of biological
compounds (to observe geometric behavior of cells and tissues) and microfluidics systems.
[attachment=41562]
Abstract
Micromachining and MEMS technologies can be used to produce complex electrical, mechanical,
fluidic, thermal, optical, and magnetic structures, devices, and systems on a scale ranging from
organs to subcellular organelles. This miniaturization ability has enabled MEMS to be applied in
many areas of biology, medicine, and biomedical engineering – a field generally referred to as
BioMEMS. The future looks bright for BioMEMS to realize (1) microsensor arrays that act as an
electronic nose or tongue, (2) microfabricated neural systems capable of controlling motor or
sensory prosthetic devices, (3) painless microsurgical tools, and (4) complete microfluidic systems
for total chemical or genetic analyses. In this paper we focused on micro fabrication,surface micro
machining, bulk micro machining, substrate bonding, non silicon fabrication and we also focused on
micro sensors like impedance sensors, polymer based sensors, electro chemical sensors, molecular
specific sensors, resonant sensors, cell based sensors and we also discussed like micro manipulators,
surgical micro instruments, micro pumps, micro valves, micro needle, micro filters, micro valves and
then finally we concluded after mentioning some micro systems useful for different analysis.
INTRODUCTION:
Microelectromechanical systems (MEMS) is a technology of miniaturization that has been largely
adopted from the integrated circuit (IC) industry and applied to the miniaturization of all systems
(i.e., not only electrical systems but also mechanical, optical, fluidic, magnetic, etc).
Miniaturization is accomplished with microfabrication processes, such as micromachining, that
typically use lithography, although other non-lithographic precision microfabrication techniques
exist (FIB, EDM, laser machining). Due to the enormous breadth and diversity of the field of
MEMS, the acronym is not a particularly apt one. However, it is used almost universally to refer to
the entire field (i.e., all devices produced by micromachining). Other names for this general field
include “microsystems”, popular in Europe, and “micromachines”, popular in Asia.
MICROFABRICATION:
Although many of the microfabrication techniques and materials used to produce MEMS have
been borrowed from the IC industry, the field of MEMS has also driven the development and
refinement of other microfabrication processes and non-traditional materials.
Conventional IC Processes and Materials:
photolithography; thermal oxidation; dopant diffusion; ion implantation; LPCVD; PECVD;
evaporation; sputtering; wet etching; plasma etching; reactive-ion etching; ion milling - silicon;
silicon dioxide; silicon nitride; aluminum Additional Processes and Materials used in MEMS:
anisotropic wet etching of single-crystal silicon;deep reactive-ion etching or DRIE; x-ray
lithography; electroplating; low-stress LPCVD films; thick-film resist (SU-8); spin casting;
micromolding; batch microassembly
piezoelectric films such as PZT; magnetic films such as Ni, Fe, Co,
and rare earth alloys; high
temperature materials such as SiC and ceramics; mechanically robust aluminum alloys; stainless
steel; platinum; gold; sheet glass; plastics such as PVC and PDMS
The methods used to integrate multiple patterned materials together to fabricate a completed
MEMS device are just as important as the individual processes and materials themselves. The two
most general methods of MEMS integration are described in the next two sub-sections: surface
micromachining and bulk micromachining.
Substrate Bonding:
Silicon, glass, metal and polymeric substrates can be bonded together through a variety of
processes (i.e.,fusion bonding, anodic bonding, eutectic bonding, and adhesive bonding). Typically
at least one of the bonded substrates has been previously micromachined. Substrate bonding is
typically done to achieve a structure that is difficult to form otherwise (i.e., large cavities that may
be hermetically sealed or a complex system of enclosed channels) or simply to add mechanical
support and protection.
Plastic Molding with PDMS:
Polydimethylsiloxane (PDMS) is a transparent elastomer that can be poured over a mold (e.g., a
wafer with a pattern of tall SU-8 structures), polymerized, and then removed simply by peeling it
off of the mold substrate. The advantages of this process include
(1) many inexpensive PDMS parts can be fabricated from a single mold,
(2) the PDMS will faithfully reproduce even sub-micron features in the mold,
(3) PDMS is biocompatible and thus can be used in a variety of BioMEMS applications, and
(4) since PDMS is transparent, tissues, cells, and other materials can be easily imaged through it.
Common uses of PDMS in biomedical applications include: microstamping of biological
compounds (to observe geometric behavior of cells and tissues) and microfluidics systems.