Technology Bulletin

Keep the baby drier with jelly-like gels

Novel biodegradable and biologically active hydrogels may prove helpful for delivering medications and anchoring biological substances such as skin and vascular tissues. These new biomaterials contain enormous amounts of water, which make them more biocompatible with the human body, says C.C. Chu, professor of fiber science at Cornell University (Ithaca, NY). Plus they have greater mechanical strengths, integrity, and stability than other hydrogels, he adds. Chu and his research team can manipulate different properties of the substance, including how much they swell, their strength, and biodegradation rates. In addition to controlling and delivering medications and serving as biodegradable networks for implants, tissue engineering and regeneration, the hydrogels may be used for coating fabrics such as diapers to help absorb liquid, as well as coating agricultural products. Jellylike hydrogels, non-biodegradable polymers like polyacrylates, can absorb and retain many times their weight without dissolving. Chu engineered two strong and versatile substances, both patent-pending. FAX: (607) 255-5373.

Driving cars with hydrogen peroxide

Researchers at Purdue University (West Lafayette, IN) are developing a new type of environmentally friendly fuel cell that runs on chemical reactions between hydrogen peroxide and aluminum and generates about 20 times more electricity per pound than car batteries, claim the developers. "It has a huge amount of energy potential," says John Rusek, an assistant professor of aeronautics and astronautics at Purdue, who is working with students to develop the cell. The hydrogen peroxide serves two roles: it is a "catholyte," meaning it is both the electrolyte, a liquid that conducts electricity and allows the reaction to occur, and also the cathode, or the portion of the battery that attracts electrons. The aluminum serves as the cell's fuel and its anode; as it oxidizes, it gives up electrons. Waste products include water and recyclable chemical compounds. The experimental cells do not immediately provide a steady supply of electricity. It takes about two hours for the cells to reach their peak electrical output before producing a steady current flow. If perfected, such an electricity source could one day replace conventional batteries in many applications, including portable electronic equipment, Rusek says. A poster paper about the research was presented in November,1999 during the Second International Hydrogen Peroxide Propulsion Conference at the University. Call: (765) 494-4782 or e-mail: rusek@ecn.purdue.edu.   

Find those aircraft cracks with a little laser heat

Aerospace engineers from the University of Cincinnati combined an infrared laser with an ultrasonic inspection system and what did they get? A great way to find and measure tiny cracks in aircraft components. In fact, researchers say this system is ten times as accurate as previous techniques and allows for earlier detection of aircraft fatigue. Sounds great to me...someone who flies frequently! The technique, developed by Zhongyu Yan and Peter Nagy, is based on a conventional ultrasonic flaw detector with a pulsed Nd:YAG laser that highlights the parts of the ultrasonic echo coming from fatigue cracks. The laser beam, pulsed at 50 hertz or half the rate of the ultrasound signal, heats the near-surface region of the sample so that the metal undergoes thermal expansion. This causes stresses that momentarily close the relatively tight fatigue cracks but do not have much effect on features like corrosion pits, coarse grains, and rivet holes, which also scatter the signal. The crack signals modulate at the irradiation frequency, blinking after each pulse, which allows a person to identify them.

Semiconductor technology gets a little boost

The fabrication of three dimensional (3D) multi-wafer stacks just got a little easier with the development of an 8-inch "face-to-face" wafer bond aligner developed by Electronic Visions Inc. (Phoenix, AZ). These EV640 aligners are equipped with SmartView software technology that allows Focus Center-New York, Rensselaer (Troy, NY) researchers to achieve micron level alignment between both the top and bottom wafers using visible light technology. Prior to Electronic Visions' system, micron-level alignment of multiwafer 3D interconnects was not practical, say Electronic Vision officials. At the Focus Center-New York, researchers address roadblocks to achieving gigascale device integration, enabling the semiconductor industry to transcend limits on interconnects. "Wiring semiconductor circuits with the EV640 SmartView system will permit a significant reduction in circuit routing density and help keep interconnects from limiting IC (integrated circuit) speed," says Timothy Cale, director of the center. FAX (602) 437-9435.