Monday, November 23, 2009

Today's most noteworthy pencils, styluses, and pen scanners

Hand Tools
"Mechanical pencils rule," my fifteen-year-old grandniece, Genevieve, declared when I invited her to be her generation's voice
on school supplies. "Nobody sharpens anymore." Then, continuing with a fashion maven's hyperbole and arbitrary imperatives, she gave a passionate disquisition on types of clickers, new grips, smaller lead sizes, and other niceties of pencil selection. As she consigned the yellow-painted wooden pencil to the wastebasket of history, I felt a rush of nostalgia for the perfumed sharpener shavings of my youth.


In fact the classic wooden pencil is hardly extinct, but one need only take a quick look at the array of vibrantly colored, subtly textured, high-attitude, low-priced mechanical pencils widely available to see that this writing instrument has become a part of contemporary youth culture.
 
The emotional appeal of pencils is that they are the instruments of works in progress—the quick sketch of the artist, the lines drawn by the carpenter, the notes and speculations of the scientist. Often they are the tools of people who are themselves works in progress: those in school, trying to figure the world out. Many people never quite get over the allure of school supplies, those first tools of intellect. Throughout their lives they continue to seek out and acquire pencils and pens—and now newer items such as Palm Pilots and pen-shaped scanners
I had long thought of the mechanical pencil as the dandy of the desk set, an ostentatious substitute for the modest, perfect wooden pencil. In fact the mechanical pencil has changed, though so gradually that its progress has gone largely unheralded. Today you can spend just a few dollars and get a pencil that is easier and more comfortable to use than one that was top of the line, and expensive, two decades ago.

 
Most contemporary mechanical pencils have clickers or ratchet systems to advance the lead in very small increments, which reduces the likelihood that you will break the point. They make a fine yet dark line because they use slimmer leads that have been engineered to reduce breakage. The most recent innovations involve ergonomic hand grips that have been softened in some cases and reshaped in others to increase comfort and decrease the possibility of doing damage to one's hand. The mechanical pencil that finally won me over was a Sanford PhD, which has a fashionably large body; a tapered, textured, three-sided grip; and a sleeve into which the lead can retract. It costs about $8.00.
 
You can pay hundreds of dollars for a pencil, but its mechanism will be essentially the same as that in the pencils that cost much less. "There are a couple of factories in Japan that make the works for everybody," Marilyn Brown told me. She runs the "fine writing" department at the New York specialty writing store Art Brown (www.artbrown.com), named for her husband's late uncle. "But the guys who shop here aren't going to use a two-dollar pencil. They want to show off."
 
Brown took from her display case a mechanical pencil by Faber-Castell, a leading maker of traditional wooden pencils, and let me examine it. Its barrel was made of ribbed Pernambuco wood. "This is just like an old wood pencil," she said of the elegant object in my hand, "except that it costs $195." Then she handed me a $26.95 model from the same manufacturer, called the E-Motion. It had a wooden barrel, a brushed-metal clip, and an extra-thick 1.4mm lead, thus evoking both mechanical and wooden pencils of bygone days in a smoothly contemporary form. "This," she said, "is a real pencil pencil."





Researcher gives robotic surgery tools a sense of touch

Haptic technology will allow doctors to 'feel' the work of a mechanical helper

By substituting mechanical instruments for human fingers, robotic tools give surgeons a new way to perform medical procedures with great precision in small spaces. But as the surgeon directs these tools from a computer console, an important component is lost: the sense of touch.


Johns Hopkins researchers are trying to change that by adding such sensations, known as haptic feedback, to medical robotic systems. "Haptic" refers to the sense of touch.

"The surgeons have asked for this kind of feedback," says Allison Okamura, an associate professor of mechanical engineering at Johns Hopkins. "So we're using our understanding of haptic technology to try to give surgeons back the sense of touch that they lose when they use robotic medical tools."

Okamura is a leading researcher in human-machine interaction, particularly involving mechanical devices that convey touch-like sensations to a human operator. In recent years, she has focused on medical applications as a participant in the National Science Foundation Engineering Research Center for Computer-Integrated Surgical Systems and Technology, based at Johns Hopkins. With funding from the National Institutes of Health and the NSF, she has established a collaboration with Intuitive Surgical Inc., maker of the da Vinci robotic system used in many hospitals for heart and prostate operations.

In the da Vinci system, a surgeon sits at a computer console, looks through a three-dimensional video display of the surgery site and moves finger controls that direct the motion of robotic tools inside the patient. Currently, this system does not send haptic feedback to the surgeon to convey what the mechanical tool "feels" inside the body. Okamura's team seeks to add these sensations to the da Vinci and similar machines.

Through the arrangement with Intuitive Surgical, Okamura's lab has acquired da Vinci hardware and software that allow her to conduct experiments toward achieving that goal. For example, the da Vinci's tools can be directed to tie sutures, but if the operator causes the tools to pull too hard, the thread can break. The Johns Hopkins researchers want the human operator to be able to feel resistance when too much force is applied.

"The sense of touch is important to surgeons," Okamura says. "They like to feel what's happening when they're working inside the body. They feel a 'pop' when a needle pokes through tissue. They can feel for calcification. Their sense of touch helps tell them where they are within the body. In robotic procedures and other types of minimally invasive surgery, surgeons insert long tools between their hands and the patient. This approach has definite medical benefits, but for the surgeon, there's a loss of dexterity and haptic information. It's like operating with chopsticks that have grippers on the end."

To address this, Okamura's team is experimenting with several techniques that could give some of those sensations back to the surgeons. One option is to attach to the robotic tools force sensors capable of conveying to the human operator how much force the machine is applying during surgery. Another idea is to create mathematical computer models that represent the moves made by the robotic tools, and then use this data to send haptic feedback to the operator.


Both approaches have advantages and drawbacks. Force sensors may be highly accurate, but they are expensive and would have to be made of sterile, biocompatible materials in order to to be used in medical robots. Computer models could be less expensive but might not respond quickly enough. "I'm exploring both approaches to see which produces the best results," Okamura says. "The most important thing is that the haptic feedback sent to the human operator must feel right because the fingers aren't easily fooled."

While this research continues, Okamura's team has developed an interim system that instead sends "haptic" information to the eyes. When a surgeon is using a robotic tool to tie a suture, for example, a colored circle follows the image of the tool in the visual display, indicating how much force is being using. A red light may signal that too much force is being applied, and the thread is likely to break. Green and yellow lights may indicate that the right amount of force is being used or that the tool is edging toward excessive force.

Development and use of a new high-frequency, low mechanical impedance strain gauge

A low mechanical impedance strain gauge that imposed insignificant preload to the myocardial fibers was tested in vitro and in vivo. The dynamic response of the gauge to an abrupt change in length (step response) and to sinusoidal perturbation was determined. The electrical output reached 95% of maximum steady-state response within 3-5 ms after a step displacement. Frequency analysis indicated a flat response up to 80 oscillations/s. The in vivo testings of the gauges were performed on intact, working swine hearts during control and ischemic flows in a regionally perfused preparation. During control perfusion the gauges demonstrated epicardial shortening in systole and early-to-mid diastole. Relaxation was confined to late diastole. With ischemic perfusion there was a progressive loss of systolic shortening, but minimal disruption in global hemodynamics. Correlative measurements were also made with sonomicrometers positioned in subepicardial myocardium. Patterns of motion, shortening, and changes in strain were similar between the two types of gauges.

Sunday, November 15, 2009

Small Mechanical Forces Have Big Impact On Embryonic Stem Cells

Applying a small mechanical force to embryonic stem cells could be a new way of coaxing them into a specific direction of differentiation, researchers at the University of Illinois report. Applications for force-directed cell differentiation include therapeutic cloning and regenerative medicine.


"Our results suggest that small forces may indeed play critical roles in inducing strong biological responses in embryonic stem cells, and in shaping embryos during their early development," said Ning Wang, a professor of mechanical science and engineering at the U. of I., and corresponding author of a paper accepted for publication in Nature Materials and posted on the journal's Web site.

Cell softness is an intrinsic property of embryonic stem cells and dictates how a cell responds to forces in its physical microenvironment. Those responses include how strongly the cell attaches to a surface, how far the cell spreads on a surface, and, most surprisingly, whether specific genes are expressed.

To study cellular sensitivity to force, Wang and his collaborators first attached a magnetic bead, 4 microns in diameter, to the surface of a living embryonic stem cell. Then they applied a tiny oscillating magnetic field, which moved the bead up and down. By precisely measuring the magnetic field and the distance the bead traveled, the effect of the mechanical force and how soft the cells are could be determined.

The cyclic nature of the mechanical force is very important, Wang said, as it simulates natural forces within a living cell, such as the cyclic movement of the motor protein myosin.

The researchers found that mouse embryonic stem cells were softer and much more sensitive to localized cyclic forces than their more advanced, differentiated counterparts.

"As stem cells differentiate, they become stiffer," said Wang, who is affiliated with the university's Beckman Institute, Micro and Nanotechnology Laboratory, and department of bioengineering. "The stiffer the stem cell, the less it spreads under stress."

The researchers obtained the same results when they applied cyclic forces to stiff human muscle cells. They did not experiment with human embryonic stem cells.

To study some of the long-term effects of localized mechanical forces on the behavior of mouse embryonic stem cells, the researchers utilized the expression of an enhanced green fluorescent gene. Cells expressing this gene glow fluorescent green when exposed to blue light.

As the mechanical force was applied in the researchers' experiments, the green fluorescence in cells with magnetic beads faded, indicating reduced gene expression. Control cells (without beads) a few microns away continued to glow.

"The softness of mouse embryonic stem cells makes them very sensitive to localized cyclic forces," Wang said. "If our findings can be extended to early animal embryos, they could provide a new way of locally differentiating a single cell of early lineage, while leaving nearby cells alone."

With Wang, co-authors of the paper are graduate student and lead author Farhan Chowdhury, postdoctoral research associates Sungsoo Na (now an assistant professor at Indiana University) and Dong Li, graduate student Yeh-Chuin Poh, animal sciences professor Tetsuya S. Tanaka, and cell and developmental biology professor Fei Wang.


The work was funded by the National Institutes of Health, the U.S. Department of Agriculture, and the University of Illinois

Automated mechanical monitoring system from InnerSense prevents wafer handling issues

Product Briefing Outline: InnerSense LTD (a Ricor company) now offers a new wafer handling analysis product, the SMW2, for automated mechanical monitoring of the 300mm semiconductor process tools. The new product offering is based on over 6 years of experience in preventing excursions related to wafers’ micro-cracks and other mechanical defects, as well as providing capabilities to detect worn-out process tool mechanical components and to plan more effective periodic maintenance.


Problem: Wafer handling issues are responsible for about 30% of the overall yield loss in the fab. Collision, skidding, rubbing and abrupt lifting and chucking cause wafer micro cracks, breakage, and backside/edge defects. Any mechanical contact with the wafer is suspected to generate particles. The more aggressive such contact is, the higher the particle size and count are likely to be. In addition, troubleshooting and reactive maintenance of those handling issues impacts tool availability and disrupts production. Periodic monitoring of the entire wafer handling system by means of an instrumented wafer (Smart Wafer) has been shown to pinpoint the root cause of such issues and confirm the effectiveness of a corrective action taken. This method has been adopted and implemented by leading IC manufacturers and equipment suppliers. However, in the existing method the smart wafer is manually loaded from the docking station into a FOUP. This operation requires a special tool for opening the FOUP. It has to be done in a specific area in the clean room, and the wafer needs to be cleaned before the run. In addition the raw data recorded in the old method required expert analysis to return a meaningful diagnosis. This has limited its usage in high-volume manufacturing environment.

Solution: The new product provides customers with the capability of monitoring the process tools mechanical health, using the new “Smart FOUP” which interfaces with the process tools like any standard FOUP. New GUI software includes additional user friendly analysis capabilities, such as automatic SPC tool monitoring, tool-to-tool performance comparisons, and more. The new product employs simplified routines that can be easily implemented in a high volume manufacturing environment with minimal interference with the normal production flow.

Applications: Troubleshooting, monitoring and predicting mechanical failures in any robotic wafer handling system. Could be also used by OEMs to select moving components and improve mechanical design.

Platform: The new Smart Wafer- SMW2- incorporates contact less communication and charging to allow regular robotic handling in and out of the “Smart FOUP”.. In the new product. the docking station is integrated into a dedicated FOUP. The data is downloaded via optical communication and the battery is recharged via induction, so that no mechanical contact is made with the wafer. Hence, the smart wafer can be handled like any other production or test wafer. Gathering periodic readings of every tool on the floor supports historical tracking and comparison of similar tools, enabling closer tool matching for tighter process and equipment control. It also allows harnessing the power of AEC (Automated Equipment Control) for managing the entire line through the central factory data system. Predictive maintenance can be more effective by addressing only the trending up or "out of control" mechanical parts Collaboration between the tool manufacturer and the user in sharing typical vibration signatures and indicative signals may facilitate reliable diagnosis and remote assistance. In the long run such collaboration will inevitably contribute to improving handling system designs and enhancing yields


Wednesday, November 4, 2009

Small Mechanical Forces Have Big Impact On Embryonic Stem Cells


Applying a small mechanical force to embryonic stem cells could be a new way of coaxing them into a specific direction of differentiation, researchers at the University of Illinois report. Applications for force-directed cell differentiation include therapeutic cloning and regenerative medicine.

"Our results suggest that small forces may indeed play critical roles in inducing strong biological responses in embryonic stem cells, and in shaping embryos during their early development," said Ning Wang, a professor of mechanical science and engineering at the U. of I., and corresponding author of a paper accepted for publication in Nature Materials and posted on the journal's Web site.

Cell softness is an intrinsic property of embryonic stem cells and dictates how a cell responds to forces in its physical microenvironment. Those responses include how strongly the cell attaches to a surface, how far the cell spreads on a surface, and, most surprisingly, whether specific genes are expressed.

To study cellular sensitivity to force, Wang and his collaborators first attached a magnetic bead, 4 microns in diameter, to the surface of a living embryonic stem cell. Then they applied a tiny oscillating magnetic field, which moved the bead up and down. By precisely measuring the magnetic field and the distance the bead traveled, the effect of the mechanical force and how soft the cells are could be determined.

The cyclic nature of the mechanical force is very important, Wang said, as it simulates natural forces within a living cell, such as the cyclic movement of the motor protein myosin.

The researchers found that mouse embryonic stem cells were softer and much more sensitive to localized cyclic forces than their more advanced, differentiated counterparts.

"As stem cells differentiate, they become stiffer," said Wang, who is affiliated with the university's Beckman Institute, Micro and Nanotechnology Laboratory, and department of bioengineering. "The stiffer the stem cell, the less it spreads under stress."

The researchers obtained the same results when they applied cyclic forces to stiff human muscle cells. They did not experiment with human embryonic stem cells.

To study some of the long-term effects of localized mechanical forces on the behavior of mouse embryonic stem cells, the researchers utilized the expression of an enhanced green fluorescent gene. Cells expressing this gene glow fluorescent green when exposed to blue light.

As the mechanical force was applied in the researchers' experiments, the green fluorescence in cells with magnetic beads faded, indicating reduced gene expression. Control cells (without beads) a few microns away continued to glow.

"The softness of mouse embryonic stem cells makes them very sensitive to localized cyclic forces," Wang said. "If our findings can be extended to early animal embryos, they could provide a new way of locally differentiating a single cell of early lineage, while leaving nearby cells alone."


With Wang, co-authors of the paper are graduate student and lead author Farhan Chowdhury, postdoctoral research associates Sungsoo Na (now an assistant professor at Indiana University) and Dong Li, graduate student Yeh-Chuin Poh, animal sciences professor Tetsuya S. Tanaka, and cell and developmental biology professor Fei Wang.

The work was funded by the National Institutes of Health, the U.S. Department of Agriculture, and the University of Illinois.

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