Harvesting energy from the environment makes it possible to deploy tiny sensors for long periods of time, with little or no required maintenance; however, this free energy makes testing and experimentation difficult. Environmental energy sources vary widely and are often difficult both to predict and to reproduce in the lab during testing. These variations are also behavior dependent—a factor that leaves application engineers unable to make even simple comparisons between algorithms or hardware configurations, using traditional testing approaches. In this article, we describe the design and evaluation of Ekho, an emulator capable of recording energy harvesting conditions and accurately recreating those conditions in the lab. This makes it possible to conduct realistic and repeatable experiments involving energy harvesting devices. Ekho is a general-purpose, mobile tool that supports a wide range of harvesting technologies. We demonstrate, using a working prototype, that Ekho is capable of reproducing solar, Radio Frequency (RF), and kinetic energy harvesting environments accurately and consistently. Our results show that Ekho can recreate harvesting-dependent program behaviors by emulating energy harvesting conditions accurately to within 77.4μA for solar and 15.0μA for kinetic environments, and can emulate RF energy harvesting conditions consistently.

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Purchased equipment for teaching basic electronics can be expensive. It may also be delicate and, in the case of many prototyping circuit boards, so small that students have trouble visualizing the circuit before them and instructors cannot easily figure out what the student has done wrong when asked for help. This paper describes a versatile circuit board system that can be built for about $100 in parts. It contains its own DC power supply, voltmeters, and large blocks with which basic electronic components may be arranged and interconnected using large wires and banana plugs. Typical lab projects using the board involve DC and AC circuits, relays, diodes, op amps and other IC devices. These projects guide students through exercises using a combination of the actual circuit and a Multisim TM simulation. A web site is given from which lab manuals may be obtained.

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