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February 2017 • The PCB Magazine 63 EIPC WORKSHOP ON PCB BIOMEMS Computer Science and Elec- trical Engineering at the University of Rostock, Ger- many. Prof. Pagel contrasted the differences between us- ing silicon and PCB technol- ogies for MEMs. He noted the advantage of rapid pro- totyping with PCB MEMs, but identified the disadvantages of minimum feature size in the 20- to 100-micron range and the relatively high tolerances. But he asked, "Who needs nano structures?" Pagel went on to explain that systems could be categorized into two basic structures, micro- structures in the range of 10 to 300 microns and macrostructures in the range of 0.3 to 10 mil- limetres. He explained that microstructures are characterised by low flow and features produced by chemical processes whereas macrostructures are characterised by high flow and features pro- duced by mechanical milling processes. Some systems integrate both micro and macro chan- nels in a single package and Pagel considered the key to success was the integration of mi- crofluidics and electronics in a stacked system. He described a project whereby apertures to be used as microfluidic channels were formed in a PCB structure using multilayer lamination tech- niques. Pagel explained that the project faced some challenges, especially of delamination in the low-pressure areas but these were eventually overcome using a two-stage production tech- nique and the application of no flow prepregs. The next example was that of a CO2 insuf- flator, which is a device used to inflate body cavities during laparoscopic surgery and other minimally-invasive surgical procedures. These devices use flow rates of between one and 45 litres of gas per minute and achieve an intraab- dominal pressure in the range of nine to 15 mmHg. Pavel showed the PCB design using em- bedded channels instead of discrete piping and integrated flow and pressure sensors. The PCB version of the insufflator achieved a significant size reduction from its predecessor and a cost reduction of 75%. Pavel concluded by showing an example of a micro PCR (polymerase chain reaction) de- vice for in vitro amplification of specific DNA or RNA sequences, allowing small quantities of short sequences to be analysed without cloning. PCR is a technique used in the diagnosis and monitoring of genetic diseases and studying the function of a targeted segment of DNA. The microfluidics version uses four integrated heat- ing zones and eight CV (coefficient of variation) sensors in a single unit. The advantages of using PCB technology for this device were explained as short prototyping timeframe, low cost pro- duction and miniaturisation. Dr. Angeliki Tserepi of The Institute of Nanosci- ence & Nanotech at the National Centre for Scien- tific Research "Demokritos," Greece took the podium next. Tserepi expanded on the theme of DNA amplifi- cation principles using PCR and isothermal amplification, explaining that traditional techniques required 2–3 days for di- agnosis; however, using a PCB solution could reduce that time to three hours. A microPCR design was shown fabricated on a thin flexible polyimide substrate with copper heaters defin- ing each of the three thermal zones and a plasma- etched microfluidic channel. A flow rate of 8 μl per minute was established as the maximum flow rate for good linearity of the DNA amplification. Simulations performed allowed optimisation of parameters to achieve temperature uniformity and linearity of the temperature/resistance curve. The device demonstrated integration in lab-on-chip for a DNA-based pathogen detection system with sufficient amplification comparable to conventional thermocyclers. The system can use different thermal and flow templates to enable detection of a wide range of pathogens including salmonella for food safety and mycoplasma for pneumonia. The benefits of using PCB technology for the system were explained as being quick, cheap, low power, reproducible and amenable to mass production. In addressing point of care/point of need diagnostics, food safety and in-the- field environmental analysis. Dr. Tserepi ended with showing a video animation of a prototype portable micronanobiosystem and instrument for ultra-fast analysis of pathogens in food. Prof. Lienhard Pagel Dr. Angeliki Tserepi