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84 DESIGN007 MAGAZINE I OCTOBER 2019 Andy Shaughnessy is managing editor of Design007 Magazine. He has been covering PCB design for 19 years. He can be reached by clicking here. R&D. But with the strong flex demand from carmakers and handheld device manufac- turers, it appears that "the juice is worth the squeeze," as my grandfather would say. We begin this month's edition of Flex007 with an interview with Kelly Dack, a design in- structor with EPTAC who has been designing flex for years. He discusses some of the most cutting-edge flex technologies he's seen late- ly, including flex-to-metal lamination, and why it's so important for flex designers to commu- nicate with fabricators and develop a thorough understanding of the final product. Next, columnist Mike Carano of RBP Chemi- cal Technology explains what technologists ac- customed to rigid boards need to know about working with flex and rigid-flex, including dif- ficulty getting metallization to adhere to poly- imide. Then, Dominique Numakura of DKN Research provides a look into printed electron- ic circuit (PEC) processes with a comparison of the subtractive and PEC techniques, as well as the associated costs. Has your company ever worked with PEC? I hear a lot of talk about printed electronics, but I don't see many real- world applications. PEC may never replace tra- ditional PCBs, but the process is so simple and cost-effective that I imagine it will find its own niche eventually. We're right in the middle of show season now, and I-Connect007 is ready to roll. We'll be providing video coverage of productron- ica in Munich, and in November, I'll be at PCB Carolina—a show sponsored by the Re- search Triangle Park (RTP) Chapter of the IPC Designers Council. If you can't make it to a show, don't worry; we'll be there. See you next month! FLEX007 To analyze tiny amounts of liquids, scientists often use devices called microfluidic chips, which are small pieces of plastic that are etched or molded with minuscule chan- nels. Although these single-use chips are small, their wide- spread use in labs, hospitals, and point-of-care situations adds up to a lot of plastic pollution. Now, researchers re- porting in the American Chemical Society (ACS) journal An- alytical Chemistry have developed versatile microfluidic chips made of a renewable, biodegradable, and inexpen- sive resource: wood. Microfluidic chips are useful for analyzing small sam- ples, like a single drop of blood, at low cost because only minuscule amounts of expensive re- agents are needed. When a fluid flows through the microchannels, it is mixed with certain substances and then an- alyzed, for example, for the presence of microbes or disease-related pro- teins. Recently, scientists have tried making microfluidic chips from inex- pensive, environmentally friendly re- sources, such as cloth or paper, but these devices are typically limited to relatively simple ap- plications. To make their device, the researchers used a laser printer to engrave tiny channels into birch plywood chips. Then, to prevent liquids from seeping into the porous wood, they coated the channels with a thin layer of Tef- lon. When they introduced blue and red food dyes to the tips of Y- and T-shaped patterns of channels, the liquids mixed as efficiently in the wood chips as in conventional plastic devices. The researchers also used the wood chips, in conjunction with a fluorescence technique, to measure the amounts of two proteins and live bacteria, all of which were similar to the amounts de- termined by a plastic chip. The wood devices were 10—100 times less ex- pensive than comparable plastic ones and more environmentally friend- ly. Now, the researchers are working on finding a renewable replacement, such as beeswax or natural oils, for the Teflon coating. (Source: ACS) Microfluidic Devices Made of Wood