The Internet of Disposable Things Will Be Made of Paper and Plastic Sensors

#News(IoTStack) [ via IoTForIndiaGroup ]

IoT is possible now because of the convergence of low-cost, low-power components, specifically microprocessors, cellular radios, Wi-Fi radios, and MEMS sensors. IHS Markit, a research firm that tracks and analyzes the electronics industry, predicts that the global volume of IoT devices will more than quadruple, from 27 billion connected devices in 2017 to 125 billion in 2030.

To say that the semiconductor industry is excited would be a huge understatement. Underlying that excitement is a major assumption—that all of these components will be made using silicon, leveraging existing billion-dollar chip factories known as fabs.

The sensors available for IoT applications today are based on MEMS (microelectromechanical systems). Fabricated on silicon wafers using methods developed originally for making semiconductor ICs, MEMS sensors use microscopic mechanical structures to detect motion, sound, pressure, light, or even species of gas. Tiny diaphragms, cantilevers, vibrating masses, or circuitous channels, usually smaller than 100 micrometers (the diameter of a human hair), respond to a physical stimulus and then transduce it to an electronic signal. When coupled to a radio and antenna, MEMS sensors can send their electronic data wirelessly to the Internet.

Researchers have been working on paper and plastic sensors for years, and lowering the cost of sensors hasn’t been their only motivation. Competition for federal funds has led researchers to seek ways to make microtechnology without clean rooms and other exotic tools. Then there’s the rising interest in constructing sensors out of materials more flexible and biodegradable than silicon, for use in invasive medical applications. And as electronics applications embrace the entire world, there’s a growing need in developing countries to make use of the ultimate low-cost material—paper.

One of CardioMEMS’s cofounders, the University of Pennsylvania’s Mark Allen, subsequently shifted away from rigid silicon and quartz sensors to making flexible and biodegradable sensors. Graduate students in Allen’s group are now engineering sensors and even batteries from polymers such as poly(lactic co-glycolic) acid (PLGA), polyvinyl alcohol (PVA), and polycaprolactone (PCL), the same materials used in dissolvable surgical sutures. Interconnects and antennas are formed from biodegrading metals such as magnesium or zinc. Using MEMS microfabrication techniques such as photolithography and electroplating, the students have demonstrated biodegradable, millimeter-size pressure sensors with the same wireless data-transmission capability of their quartz ancestors

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