Paul Worgan

PowerShake: Power Transfer Interactions for Mobile Devices

Current devices have limited battery life, typically lasting less than one day. This can lead to situations where critical tasks, such as making an emergency phone call, are not possible. Other devices, supporting different functionality, may have sufficient battery life to enable this task. We present PowerShake; an exploration of power as a shareable commodity between mobile (and wearable) devices. PowerShake enables users to control the balance of power levels in their own devices (intra-personal transactions) and to trade power with others (inter-personal transactions) according to their ongoing usage requirements. This paper demonstrates Wireless Power Transfer (WPT) between mobile devices. PowerShake is: simple to perform on-the-go; supports ongoing/continuous tasks (transferring at ~3.1W); fits in a small form factor; and is compliant with electromagnetic safety guidelines while providing charging efficiency similar to other standards (48.2% vs. 51.2% in Qi). Based on our proposed technical implementation, we run a series of workshops to derive candidate designs for PowerShake enabled devices and interactions, and to bring to light the social implications of power as a tradable asset.

Garment level power distribution for wearables using inductive power transfer

Wearable and smart devices are gaining in popularity, with many users now using multiple devices. Each of these devices requires individual charging and power maintenance. This paper proposes power sharing between multiple wearables to alleviate some of the burden of charging multiple devices. To achieve wearable and smart device power sharing, we propose using the garments we wear as a power distribution backbone. To allow non-contact power transfer between garments, bi-directional inductive power transfer is used. We demonstrate a novel coil topology called Feed Coils constructed from flexible materials to aid garment integration and user comfort. Our system complies with international guidelines on time-varying magnetic field exposure to human tissue, allowing the system to be operated in close proximity to the body. Three preliminary experiments are conducted to characterize the bi-directional inductive power sharing system and to investigate the feasibility and human factors impacting wearable and smart device power sharing.

Flexible on-body coils for inductive power transfer to IoT garments and wearables

Inductive power transfer is a promising technology for ambient charging and powering of wearable devices without the need for direct user intervention. Existing systems typically use circular or rectangular coils built using inflexible wire and fixed into a rigid shape. This paper explores the design of receiver coils for wearable inductive power transfer. Our study demonstrates receive coil designs that visually embody patterns or logos do not significantly reduce receive voltage compared to a traditional wire loop of the same number of turns, giving designers flexibility over the appearance of wearable power transfer coils.

Influence of exposure guidelines on the design of on-body inductive power transfer

Designers of on-body health sensing devices with inductive power transfer (IPT) face a number of trade-offs. Safe exposure limits should be maintained, and protective housing and padding are generally needed; however, these impose compromises on the power-transfer-system design. This paper analyses these trade-offs and proposes a design route to achieving high power transfer in the presence of field restrictions and separations for padding or housing materials. An IPT system using a Class D coil-driver and switched-mode power-conditioning is designed to provide regulated d.c. and energy storage. Compliance with ICNIRP 1998 guidelines is demonstrated, at a power level that is sufficient to power typical on-body medical sensing devices.

DeskWave: Desktop Interactions using Low-cost Microwave Doppler Arrays

Microwaves are a type of electromagnetic radiation that can pass through a variety of commonly found materials but partially reflect off human bodies. Microwaves are non-ionizing and at controlled levels do not pose a danger. A wave that is capable of passing through materials and image humans could have useful applications in human-computer-interaction. However, only recently the full potential of microwaves for interactive devices has begun to be explored. Here, we present a scalable, low-cost system using an array of off-the-shelf microwave Doppler sensors and explore its potential for tabletop interactions. The arrays are installed beneath a desk, making it an ubiquitous device that enables a wide range of interactions such as 3D hand tracking, gesture recognition and different forms of tangible interaction. Given the low cost and availability of these sensors, we expect that this work will stimulate future interactive devices that employ microwave sensors.

CoilMove: An Actuated to-body Energy Transfer System

Today, users are an integral part of charging their mobile and wearable computing devices, including smartphones, smartwatches, fitness trackers and music players. In this paper CoilMove is presented. CoilMove is an actuated wireless energy transfer system, envisaged as being embedded within a surface in a users ambient environment, such as a floor or table. CoilMove transfers energy to devices located on the body and can recharge our mobile and wearable devices through inductive power transfer without the need for user input. CoilMove is capable of locating a device on a users body through the presence of a magnet on the device. The user need not be aware of the interaction and from a user perspective devices would appear to charge themselves. Furthermore CoilMove is compliant with international guidelines on time-varying magnetic fields present in inductive power transfer systems, affording prolonged system use.

Force Attraction Pen: A Haptic Pen with Variable Attraction Force

We present the Force Attraction Pen, a haptic stylus that encourages the users to move in a particular direction by providing variable attraction force feedback based on their actions. The tip of the stylus is augmented with an electromagnet that can repel or attract the stylus to a metallic surface. By altering the polarity and voltage, we change the amount and direction of the force produced. The tactile expressions of the stylus may enable a higher grain of control during tasks such as tracing an image, performing selection, and other high precision tasks. In this paper we present the design and implementation of such a system, along with a formative study as a preliminary investigation into the haptic feedback generated by our system.

NotiFall: Ambient Sonification System Using Water

This paper presents NotiFall, an experimental prototype of an ambient auditory notification system. NotiFall uses the sound of falling water to subtly notify users for non-urgent matters, such as weather alerts or emails in an unobtrusive manner. These sounds are controlled and altered in order to convey a wider range of auditory cues and information. Traditionally, ambient notification systems are application specific and are limited in the way they can transmit information. In comparison, NotiFall is easily programmable, suitable for a wide range of home and work environments, and makes use of both visual and audio cues in order to impart information.

Mobile energy sharing futures

We foresee a future where energy in our mobile devices can be shared and redistributed to suit our current task needs. Many of us are beginning to carry multiple mobile devices and we seek to re-evaluate the traditional view of a mobile device as only accepting energy. In our vision, we can leverage the energy stored in our devices to wirelessly distribute energy between our friends, family, colleagues and strangers devices. In this paper we explore the opportunities and interactions presented by such spontaneous energy transfer interactions and present some envisaged collaborative energy sharing futures.