RF rectifiers for EM power harvesting in a deep brain stimulating device

A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 kΩ. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device.

Five ways to hack and cheat with bring-your-own-device electronic examinations

Bring-your-own-device electronic examinations (BYOD e-exams) are a relatively new type of assessment where students sit an in-person exam under invigilated conditions with their own laptop. Special software restricts student access to prohibited computer functions and files, and provides access to any resources or software the examiner approves. In this study, the decades-old computer security principle that ‘software security depends on hardware security’ is applied to a range of BYOD e-exam tools. Five potential hacks are examined, four of which are confirmed to work against at least one BYOD e-exam tool. The consequences of these hacks are significant, ranging from removal of the exam paper from the venue through to receiving live assistance from an outside expert. Potential mitigation strategies are proposed; however, these are unlikely to completely protect the integrity of BYOD e-exams. Educational institutions are urged to balance the additional affordances of BYOD e-exams for examiners against the potential affordances for cheaters.

Parents' perspectives on tele-AAC support for families with a new speech generating device: results from an Australian pilot study

Telepractice is rapidly gaining popularity as a cost-effective and convenient alternative to in-person services for a range of speech-language pathology (SLP) applications. To date, there has been little research investigating the use of telepractice to support families with a new speech generating device (SGD). This paper reports on the outcomes of a novel online training and support program, trialed with 4 underserviced Australian families of children with a new SGD. The program consisted of 6 video-narrated lessons on SGD use, along with an online supervision and practice component conducted via videoconference. Semistructured interviews were undertaken with parents following their completion of the program. Parents noted the telepractice support model offered a range of benefits, including convenient service access and flexible learning options. Challenges included technology limitations and increased pressure on parents to coordinate home practice. Overall, parents reported that the telepractice program was a positive experience for them and their children. Findings indicated that telepractice is a promising mode of service delivery for those learning to use a new SGD. Further research in this area is warranted.

Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO2 overlay coating on TiO2 nanoparticle working electrode

Novel TiO2 single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO2 nanorods on TiO2 nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO2 nanorods had lower dye loading than TiO2 nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO2 nanorods received less resistance than that in TiO2 nanoparticle aggregation. By just applying a thin layer of TiO2 nanorods on TiO2 nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO2 nanoparticle layer covered with 3 μm thick TiO2 nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs.

Development of a compact rectenna for wireless powering of a head-mountable deep brain stimulation device

Design of a rectangular spiral planar inverted-F antenna (PIFA) at 915 MHz for wireless power transmission applications is proposed. The antenna and rectifying circuitry form a rectenna, which can produce dc power from a distant radio frequency energy transmitter. The generated dc power is used to operate a low-power deep brain stimulation pulse generator. The proposed antenna has the dimensions of 10 mm × 12.5 mm × 1.5 mm and resonance frequency of 915 MHz with a measured bandwidth of 15 MHz at return loss of -10 dB. A dielectric substrate of FR-4 of εr = 4.8 and δ = 0.015 with thickness of 1.5 mm is used for both antenna and rectifier circuit simulation and fabrication because of its availability and low cost. An L-section impedance matching circuit is used between the PIFA and voltage doubler rectifier. The impedance matching circuit also works as a low-pass filter for elimination of higher order harmonics. Maximum dc voltage at the rectenna output is 7.5 V in free space and this rectenna can drive a deep brain stimulation pulse generator at a distance of 30 cm from a radio frequency energy transmitter, which transmits power of 26.77 dBm.

Alternative service delivery models for families with a new speech generating device: perspectives of parents and therapists

Purpose: Research has revealed limitations in the provision of in-person services to families with a new speech generating device (SGD), both in Australia and overseas. Alternative service models such as parent training, peer support and telepractice may offer a solution, but their use with this population has not been researched to date.

Method: Using interviews and focus groups, this study explored the experiences and opinions of 13 speech-language pathologists and seven parents regarding alternatives to in-person support and training for families with a new SGD. Data were analysed using grounded theory. Themes explored in this paper include the benefits and drawbacks of alternative service models as well as participants’ suggestions for the optimal implementation of these approaches.

Result: Participants confirmed the utility of alternative service models, particularly for rural/remote and underserviced clients. Benefits of these models included reduced travel time for families and therapists, as well as enhanced information access, support and advocacy for parents.

Conclusion: Participants viewed the provision of ongoing professional support to families as critical, regardless of service modality. Additional issues arising from this study include the need for development of organizational policies, resources and training infrastructure to support the implementation of these alternative service models.

Radio frequency energy harvesting from a feeding source in a passive deep brain stimulation device for murine preclinical research

This paper presents the development of an energy harvesting circuit for use with a head-mountable deep brain stimulation (DBS) device. It consists of a circular planar inverted-F antenna (PIFA) and a Schottky diode-based Cockcroft-Walton 4-voltage rectifier. The PIFA has the volume of π × 10(2) × 1.5 mm(3), resonance frequency of 915 MHz, and bandwidth of 16 MHz (909-925 MHz) at a return loss of -10 dB. The rectifier offers maximum efficiency of 78% for the input power of -5 dBm at a 5 kΩ load resistance. The developed rectenna operates efficiently at 915 MHz for the input power within -15 dBm to +5 dBm. For operating a DBS device, the DC voltage of 2 V is recorded from the rectenna terminal at a distance of 55 cm away from a 26.77 dBm transmitter in free space. An in-vitro test of the DBS device is presented.

The double sensor-a non-invasive device to continuously monitor core temperature in humans on earth and in space

The objective of our study was to establish whether rectal temperature recordings in humans could be replaced by a non-invasive skin temperature sensor combined with a heat flux sensor (Double Sensor) located at the forehead to monitor core body temperature changes due to circadian rhythms. Rectal and Double Sensor data were collected continuously for 24h in seven men undertaking strict head-down tilt bed-rest. Individual differences between the two techniques varied between -0.72 and +0.55 degrees C. Nonetheless, when temperature data were approximated by cosinor analysis in order to compare circadian rhythm profiles between methods, it was observed that there were no significant differences between mesor, amplitude, and acrophase (P>0.310). It was therefore concluded that the Double Sensor technology is presently not accurate enough for performing single individual core body temperature measurements under resting conditions at normal ambient room temperature. Yet, it seems to be a valid, non-invasive alternative for monitoring circadian rhythm profiles.

Classification of team sport activities using a single wearable tracking device

Wearable tracking devices incorporating accelerometers and gyroscopes are increasingly being used for activity analysis in sports. However, minimal research exists relating to their ability to classify common activities. The purpose of this study was to determine whether data obtained from a single wearable tracking device can be used to classify team sport-related activities. Seventy-six non-elite sporting participants were tested during a simulated team sport circuit (involving stationary, walking, jogging, running, changing direction, counter-movement jumping, jumping for distance and tackling activities) in a laboratory setting. A MinimaxX S4 wearable tracking device was worn below the neck, in-line and dorsal to the first to fifth thoracic vertebrae of the spine, with tri-axial accelerometer and gyroscope data collected at 100Hz. Multiple time domain, frequency domain and custom features were extracted from each sensor using 0.5, 1.0, and 1.5s movement capture durations. Features were further screened using a combination of ANOVA and Lasso methods. Relevant features were used to classify the eight activities performed using the Random Forest (RF), Support Vector Machine (SVM) and Logistic Model Tree (LMT) algorithms. The LMT (79-92% classification accuracy) outperformed RF (32-43%) and SVM algorithms (27-40%), obtaining strongest performance using the full model (accelerometer and gyroscope inputs). Processing time can be reduced through feature selection methods (range 1.5-30.2%), however a trade-off exists between classification accuracy and processing time. Movement capture duration also had little impact on classification accuracy or processing time. In sporting scenarios where wearable tracking devices are employed, it is both possible and feasible to accurately classify team sport-related activities.

Young children's transfer of learning from a touchscreen device

Because young children are devoting increasing time to playing on handheld touchscreen devices, understanding children's ability to learn from this activity is important. Through two experiments we examined the ability of 4- to 6-year-old children to learn how to solve a problem (Tower of Hanoi) on a touchscreen device and subsequently apply this learning in their interactions with physical objects. The results were that participants demonstrated significant improvement at solving the task irrespective of the modality (touchscreen vs. physical version) with which they practiced. Moreover, children's learning on the touchscreen smoothly transferred to a subsequent attempt on the physical version. We conclude that, at least with respect to certain activities, children are quite capable of transferring learning from touchscreen devices. This result highlights the limitations of generalizing across screen-based activities (e.g., "screen time") in discussing the effects of media on young children's development.