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Medical Edge October 21, 2008

Oct 31, 2008 2:55 PM

MED_Medical Edge_: Building strong yet lightweight hip implants

October 21, 2008

May the best man for device makers win

While considering the two main candidates running for President of the U.S., entertain this question: Which will be better for the U.S. economy, or more to the point, best for the medical- device community? To answer that question, it is useful to review the candidates' positions on medical-device development and manufacturing, especially because both candidates profess to be interested in implementing some form of national health care, or in my mind, a one-purchaser program.
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Articles

Building strong yet lightweight hip implants

How often has one of your designs been a trade-off of weight versus strength? Too heavy, and you waste material. Too light, and parts might fail. Well, here's good news. A recent technology fabricates components that are strong and lightweight. Called electron beam melting (EBM), the technique accelerates electrons to half the speed of light onto powdered metal to melt and weld the material, one layer at a time. As with other additive methods, EBM builds parts that can fill arbitrary volumes and makes for a great way to generate “lattice structures,” arrangements of repeating patterns with engineered stiffnesses. There is often no other practical way to fabricate some of these geometries.
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Medical Sealing Solutions from Apple Rubber Products

Apple Rubber designs and manufactures elastomeric seals in medical grade class VI, liquid silicone rubber, and other elastomers including, FKM and EPDM. Apple Rubber specializes in the manufacture of all shapes and sizes of O-rings, custom-molded seals, and rubber bonded to plastic, metal or filter materials. USA-based facilities include transfer, compression, liquid injection molding, CNC machining and proprietary bonding. ISO 9001-2000 and a certified class 7 (10,000) cleanroom is also onsite.

www.applerubber.com

Gripper gives surgeons a hand in microsurgery

A small handlike gripper, only about 500-µm diameter when open, can grasp tissue or cell samples making it easier for doctors to perform minimally invasive surgery, such as biopsies. The tiny device can be magnetically guided around from outside the patient. Its "fingers" curl around an object when chemically triggered. The design responds autonomously to chemical cues in the body. For example, it might react to the biochemicals released by infected tissue to remove pieces for analysis. The idea is to let surgical tools move more freely inside a body.
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Ideas and lasers build better stents

Self-expanding stents are a remarkable development. They come in a variety of sizes and designs intended for blood vessels, airways, and even intestines. They have just a few downsides. For instance, tissue tends to grow in and over bare metal designs blocking passageways that the stent was intended to help open. They may move out of place or migrate, and occasionally the pulmonary devices fatigue because coughing is so vigorous. Pulmonary stents are not as compliant with the anatomy as they could be, they may cause infections such as halitosis, and can be difficult to deploy and reposition. More than one such stent has required gruesome surgery to remove it.
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Miniature encoder keeps microscope in focus

Researchers are conducting more genetic experiments that call for use of inverted microscopes so they can view and track the activity of discrete molecules within living cells. An inverted microscope uses a light over the specimen and the objective lens below it. The resulting images reveal the nature of intracellular processes, critical information for tasks that include drug discovery, disease prevention, and biochemistry research. For successful experiments, however, inverted microscopes must stay precisely focused to capture digital time-lapse photographs of fluorescent markers. This means the objective lens on a microscope remains within 100 nm of the focal plane, thereby preventing images from drifting out of focus in time-lapse photography. For such precision, small thermal effects present big challenges. Even an ambient temperature shift of one degree Celsius can alter focus by 200 nm.
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New Products

Combination display and controller

The DS-3000 four-channel display includes controller functions. A user can connect up to four iLoad series load cells and view individual or total loads or both in three different units: kilograms, pounds, and newtons. A user can also interface by USB uplink to plot and chart data to a PC. Optional relay outputs let users activate relays based on load limits to control up to two external devices.
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Heaters get really small

Ultramic 600 advanced ceramic heaters are available in smaller sizes, a few millimeters width and several centimeters long. The high-thermal conductivity aluminum nitride ceramic composition is paired with a proprietary, thermally matched, heating element for a fast responding heater in a low-mass package. A leakage current of less than 10 µA makes the device easier for medical devices to pass the 500 µA, IEC 60601, total system requirement the first time.
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Transformers for portable medical devices

Model 4283-1250 Series high-voltage transformers drive high impedance loads requiring up to 2,500 Vdc. The application-specific units can be custom configured for portable medical devices such as defibrillators. A center-tapped secondary for the 4283-1250 Series creates positive and negative outputs. This would drive a full wave bridge rectifier, ground in the center, positive on one side, negative on the other. Or it could be used as a half-wave output providing either a positive or negative voltage.
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