Sergey Chemishkian

Feasibility of wireless sensors using ambient 2.4GHz RF energy

We present a new system for measuring ambient RF energy in the 2.4GHz ISM band. This apparatus is intended to establish the feasibility of harvesting ambient RF energy to power emerging ultra-low-power sensors and microcontrollers. We simultaneously acquire RF measurements from a spatial and polarization diversity antenna system, with both a spectrum analyzer (frequency-selective but slow), and a log amp (wideband but fast), explain key tradeoffs in the measurement configuration, and present a post-processing algorithm which provides a reliable characterization of the RF energy available in the 2.4GHz ISM band. Preliminary results suggest enough energy is available to support a low duty cycle wireless sensor node system. An average RF power of 11nW is observed 10m away from a typical Wi-Fi access point in an office environment, suggesting the possibility of low duty cycle, wirelessly powered sensing and communication using a Bluetooth Low Energy (BLE) or another ultra low power uplink.

A 2.4GHz ambient RF energy harvesting system with −20dBm minimum input power and NiMH battery storage

We describe a radio frequency (RF) energy harvester and power management circuit that trickle charges a battery from incident power levels as low as -20dBm. We designed the harvester for the 2.4 GHz RF band to leverage the ubiquity of energy that is produced by Wi-Fi, Bluetooth, and other devices. This paper reports on the design and current status of the harvester and compares our performance to other published results. In this incident power regime, rectified voltages are low, so power management circuit operation in the 100mV regime is critical. This paper describes a novel rectenna design, boost converter, and battery charger for RF energy harvesting specifically tuned to this low-power regime. At -20dBm RF input power, the harvesting system (rectenna, boost converter, and battery charger) sources 5.8μJ into a rechargeable battery after 1 hour.

46.2: Real-Time Pen Tracking on Electronic Paper Displays

On most electronic paper displays (EPDs), low update rates lead to a poor user experience especially for pen-based markups. The slow update causes a remarkable delay between pen motion and visibility of the stroke. Even worse, this delay varies depending on the current part of the update cycle. This paper presents a real-time pen tracking method for EPDs, using a new display driver on an unmodified E Ink hardware platform. This method compares favorably to the iLiad E-Reader.

Automatic Discovery and Execution of Personal Applications from Shared IO Devices

Shared office information appliances such as copiers, scanners and meeting-room displays are increasingly being integrated into complex electronic document workflows. To support this new role these appliances are being designed with advanced features such as optical character recognition, networked storage, content-based routing and integration with back-end databases, yet availability of these features is often hampered by various factors. Here we present an architecture, code named Odessa, that moves all task-specific processing off the office appliance and on to a users own device: PC / laptop, or smartphone. Key features of the architecture include a simple RESTful HTTP application interface and automatic service discovery.