5,727 research outputs found
Microsystems technology: objectives
This contribution focuses on the objectives of microsystems technology (MST). The reason for this is two fold. First of all, it should explain what MST actually is. This question is often posed and a simple answer is lacking, as a consequence of the diversity of subjects that are perceived as MST. The second reason is that a map of the somewhat chaotic field of MST is needed to identify sub-territories, for which standardization in terms of system modules an interconnections is feasible. To define the objectives a pragmatic approach has been followed. From the literature a selection of topics has been chosen and collected that are perceived as belonging to the field of MST by a large community of workers in the field (more than 250 references). In this way an overview has been created with `applications¿ and `generic issues¿ as the main characteristics
Microfabricated Implantable Parylene-Based Wireless Passive Intraocular Pressure Sensors
This paper presents an implantable parylene-based wireless pressure sensor for biomedical pressure sensing applications specifically designed for continuous intraocular pressure (IOP) monitoring in glaucoma patients. It has an electrical LC tank resonant circuit formed by an integrated capacitor and an inductor coil to facilitate passive wireless sensing using an external interrogating coil connected to a readout unit. Two surface-micromachined sensor designs incorporating variable capacitor and variable capacitor/inductor resonant circuits have been implemented to realize the pressure-sensitive components. The sensor is monolithically microfabricated by exploiting parylene as a biocompatible structural material in a suitable form factor for minimally invasive intraocular implantation. Pressure responses of the microsensor have been characterized to demonstrate its high pressure sensitivity (> 7000 ppm/mmHg) in both sensor designs, which confirms the feasibility of pressure sensing with smaller than 1 mmHg of resolution for practical biomedical applications. A six-month animal study verifies the in vivo bioefficacy and biostability of the implant in the intraocular environment with no surgical or postoperative complications. Preliminary ex vivo experimental results verify the IOP sensing feasibility of such device. This sensor will ultimately be implanted at the pars plana or on the iris of the eye to fulfill continuous, convenient, direct, and faithful IOP monitoring
Wireless Intraocular Pressure Sensing Using Microfabricated Minimally Invasive Flexible-Coiled LC Sensor Implant
This paper presents an implant-based wireless pressure
sensing paradigm for long-range continuous intraocular
pressure (IOP) monitoring of glaucoma patients. An implantable
parylene-based pressure sensor has been developed, featuring an
electrical LC-tank resonant circuit for passive wireless sensing
without power consumption on the implanted site. The sensor
is microfabricated with the use of parylene C (poly-chlorop-
xylylene) to create a flexible coil substrate that can be folded
for smaller physical form factor so as to achieve minimally invasive
implantation, while stretched back without damage for
enhanced inductive sensor–reader coil coupling so as to achieve
strong sensing signal. A data-processed external readout method
has also been developed to support pressure measurements. By
incorporating the LC sensor and the readout method, wireless
pressure sensing with 1-mmHg resolution in longer than 2-cm distance
is successfully demonstrated. Other than extensive on-bench
characterization, device testing through six-month chronic in vivo
and acute ex vivo animal studies has verified the feasibility and
efficacy of the sensor implant in the surgical aspect, including
robust fixation and long-term biocompatibility in the intraocular
environment. With meeting specifications of practical wireless
pressure sensing and further reader development, this sensing
methodology is promising for continuous, convenient, direct, and
faithful IOP monitoring
IC-integrated flexible shear-stress sensor skin
This paper reports the successful development of the first IC-integrated flexible MEMS shear-stress sensor skin. The sensor skin is 1 cm wide, 2 cm long, and 70 /spl mu/m thick. It contains 16 shear-stress sensors, which are arranged in a 1-D array, with on-skin sensor bias, signal-conditioning, and multiplexing circuitry. We further demonstrated the application of the sensor skin by packaging it on a semicylindrical aluminum block and testing it in a subsonic wind tunnel. In our experiment, the sensor skin has successfully identified both the leading-edge flow separation and stagnation points with the on-skin circuitry. The integration of IC with MEMS sensor skin has significantly simplified implementation procedures and improved system reliability
Recursive Least Squares Filtering Algorithms for On-Line Viscoelastic Characterization of Biosamples
The mechanical characterization of biological samples is a fundamental issue in biology
and related fields, such as tissue and cell mechanics, regenerative medicine and diagnosis of diseases.
In this paper, a novel approach for the identification of the stiffness and damping coefficients
of biosamples is introduced. According to the proposed method, a MEMS-based microgripper
in operational condition is used as a measurement tool. The mechanical model describing the
dynamics of the gripper-sample system considers the pseudo-rigid body model for the microgripper,
and the Kelvin–Voigt constitutive law of viscoelasticity for the sample. Then, two algorithms based
on recursive least square (RLS) methods are implemented for the estimation of the mechanical
coefficients, that are the forgetting factor based RLS and the normalised gradient based RLS
algorithms. Numerical simulations are performed to verify the effectiveness of the proposed approach.
Results confirm the feasibility of the method that enables the ability to perform simultaneously two
tasks: sample manipulation and parameters identification
Challenges in flexible microsystem manufacturing : fabrication, robotic assembly, control, and packaging.
Microsystems have been investigated with renewed interest for the last three decades because of the emerging development of microelectromechanical system (MEMS) technology and the advancement of nanotechnology. The applications of microrobots and distributed sensors have the potential to revolutionize micro and nano manufacturing and have other important health applications for drug delivery and minimal invasive surgery. A class of microrobots studied in this thesis, such as the Solid Articulated Four Axis Microrobot (sAFAM) are driven by MEMS actuators, transmissions, and end-effectors realized by 3-Dimensional MEMS assembly. Another class of microrobots studied here, like those competing in the annual IEEE Mobile Microrobot Challenge event (MMC) are untethered and driven by external fields, such as magnetic fields generated by a focused permanent magnet. A third class of microsystems studied in this thesis includes distributed MEMS pressure sensors for robotic skin applications that are manufactured in the cleanroom and packaged in our lab.
In this thesis, we discuss typical challenges associated with the fabrication, robotic assembly and packaging of these microsystems. For sAFAM we discuss challenges arising from pick and place manipulation under microscopic closed-loop control, as well as bonding and attachment of silicon MEMS microparts. For MMC, we discuss challenges arising from cooperative manipulation of microparts that advance the capabilities of magnetic micro-agents. Custom microrobotic hardware configured and demonstrated during this research (such as the NeXus microassembly station) include micro-positioners, microscopes, and controllers driven via LabVIEW. Finally, we also discuss challenges arising in distributed sensor manufacturing. We describe sensor fabrication steps using clean-room techniques on Kapton flexible substrates, and present results of lamination, interconnection and testing of such sensors are presented
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Solid Freeform Fabrication Research In Engineering Education
Because Solid Freeform Fabrication (SFF) has an extremely wide range of potential applications,
crossing traditional engineering and science boundaries, it is a technology that lends itself to
multi-disciplinary activities and projects. SFF is an ideal mechanism to present scientific
concepts including materials science and mechanics, as well as larger-scope engineering topics
such as agile manufacturing. At Milwaukee School of Engineering (MSOE), we are using SFF
technologies as a means to teach engineering concepts to undergraduate students through multidisciplinary research.
MSOE was awarded a five-year grant under the NSF Research Experiences for Undergraduates
Program (EEC-9619715) to facilitate student exploration in the field of Solid Freeform
Fabrication. Sixty undergraduates will participate in summer and academic year programs by the
year 2001. Eighteen students from around the country have participated in the program to date,
bringing with them a diverse background of university experience, skill level, and interests.
Working closely with a faculty advisor possessing expertise in a particular research area, they
have performed research on Solid Freeform Fabrication applications in the biomedical,
aerospace, architectural, manufacturing, and electronics industries.
Some ofthe keys to the success of this program include:
• Hands-on access to Solid Freeform Fabrication equipment through the facilities
ofthe MSOE Rapid Prototyping Center (SLA 250, LOM 2030, and FDM 1650).
• Close partnerships of the students with faculty and industry mentors in
specialized areas of expertise.
• Teaming with other educational institutions.
• Significant cross-pollination between projects; faculty from diverse
departments.
• Encouraging students to publish and present results at national conferences and symposia.Mechanical Engineerin
Implantable parylene-based wireless intraocular pressure sensor
This paper presents a novel implantable, wireless,
passive pressure sensor for ophthalmic applications. Two
sensor designs incorporating surface-micromachined
variable capacitor and variable capacitor/inductor are
implemented to realize the pressure sensitive components.
The sensor is monolithically microfabricated using parylene
as a biocompatible structural material in a suitable form
factor for increased ease of intraocular implantation.
Pressure responses of the microsensor are characterized
on-chip to demonstrate its high pressure sensitivity (> 7000
ppm/mmHg) with mmHg level resolution. An in vivo animal
study verifies the biostability of the sensor implant in the
intraocular environment after more than 150 days. This
sensor will ultimately be implanted at the pars plana or iris of
the eye to fulfill continuous intraocular pressure (IOP)
monitoring in glaucoma patients
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