Bert Lenaerts

Wireless powering for a self-propelled and steerable endoscopic capsule for stomach inspection

This paper describes the integration of an active locomotion module in a wirelessly powered endoscopic capsule. The device is a submersible capsule optimized to operate in a fluid environment in a liquid-distended stomach. A 3D inductive link is used to supply up to 400mW to the embedded electronics and a set of 4 radio-controlled motor propellers. The design takes advantage of a ferrite-core in the receiving coil-set. This approach significantly improves the coupling with the external field source with respect to earlier work by the group. It doubles the power that can be received with a coreless coil-set under identical external conditions. The upper limit of the received power was achieved complying with the strict regulations for safe exposure of biological tissue to variable magnetic fields. The wireless transferred power was proven to be sufficient to achieve the speed of 7cm/s in any directions. An optimized locomotion strategy was defined which limits the power consumption by running only 2 motors at a time. A user interface and a joystick controller allow to fully drive the capsule in an intuitive manner. The device functionalities were successfully tested in a dry and a wet environment in a laboratory set-up.

Omnidirectional Inductive Powering for Biomedical Implants

Omnidirectional Inductive Powering for Biomedical Implants investigates the feasibility of inductive powering for capsule endoscopy and freely moving systems in general. The main challenge is the random position and orientation of the power receiving system with respect to the emitting magnetic field. Where classic inductive powering assumes a predictable or fixed alignment of the respective coils, the remote system is now free to adopt just any orientation while still maintaining full power capabilities. Before elaborating on different approaches towards omnidirectional powering, the design and optimisation of a general inductive power link is discussed in all its aspects. Special attention is paid to the interaction of the inductive power link with the patient s body. Putting theory into practice, the implementation of an inductive power link for a capsule endoscope is included in a separate chapter.

An omnidirectional transcutaneous power link for capsule endoscopy

An inductive link is presented that can handle freedom of motion. The envisaged application is to power a wireless camera capsule used for noninvasive visual inspection of the small bowel. Up to 150 mW of usable DC power can be delivered to the capsule for the entire duration of its travel along the gastric track. The realization of the link is discussed in detail. Measured data of the link performance are presented and evaluated

Revisiting rice breeding methods – evaluating the use of rapid generation advance (RGA) for routine rice breeding

Abstract Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.

Inductive Link Design

An inductive link is created fairly easily: two coils are all that is essentially needed. Even in a far from perfect design, some signal and hence power will be coming through. The rudimentary approach of picking the largest coils available that fit the application, with an arbitrary winding type and number of turns, may in many cases satisfy the requirements. Designing an inductive link that maximises the amount of power transmitted or the operating range within the constraints of the application however, is an entirely different story.

Power Converters and Voltage Regulators

A power converter is an electronic circuit that converts electric power from one form into another. A rectifier for instance converts AC power into DC, whereas an inverter does the opposite. Cascading inverters and rectifiers results in DC/DC or AC/AC converters.

Closed-Loop Transductor-Compensated Class E Driver for Inductive Links

When a class E circuit is employed to drive an inductive link, very little tolerance is allowed on the inductance value of the transmitter coil. Deformable coils are thus not compatible with an open- loop class E design. By connecting a transductor in series with the transmitter inductance, it is possible to keep the total class E inductance constant, regardless of the transmitter coil deformation. This is achieved through a control loop that steers the transductor to the appropriate inductance value. For the realized closed-loop circuit, class E regime is maintained for inductance variations of the transmitter coil of up to 27 %. The principal advantage of transductor control compared to earlier reported techniques, is the fixed frequency of operation.

An Inductive Power Link for a Capsule Endoscope

The capsule endoscope, or wireless endoscope, turns up as example in several occasions throughout this work. This is not a coincidence, since the issues and concepts dealt with in this book regarding omnidirectional inductive powering, have been inspired directly by the application of wireless endoscopy. Thus far, no details about the application itself have been given, which is atoned for in this chapter.

Global impact of accelerated plant breeding: Evidence from a meta-analysis on rice breeding

Rice breeders in Asia and elsewhere in the world have long overlooked trying to shorten the time it takes to develop new varieties. Plant breeders have proposed a technique called Rapid Generation Advance (RGA) as a way to accelerate the results of public rice breeding programs. However, little is known about RGA’s potential impact. Here, we present the first results of a global impact study of RGA. More specifically, we calculated the multiplicator effects of RGA on the research benefits generated by conventional rice breeding programs and applied them to a meta-analysis of selected impact studies in the literature. These insights are a first crucial step in developing a targeted approach for disseminating RGA technology among rice breeders to accelerate the impact of their public rice breeding programs around the world. We show that the additional benefits due to time savings are considerable and offer some insights into the economics of breeding. Our results confirm that the adoption of accelerated breeding would lead to substantial advantages to rice breeding programs and the earlier variety release leads to significant economic benefits to society. This can be important to policy makers when reshaping their public breeding methods and optimising their return on research investments in breeding.

Global survey of rice breeders to investigate characteristics and willingness to adopt alternative breeding methods

BackgroundDespite the critical role rice breeders play to ensure food security, there is a lack of information regarding their current socio-economic characteristics, constraints and attitudes towards technology adoption. Some key concepts like budget, experience, local ecosystems, level of education and even main breeding method have hardly been surveyed in the past. This not only clouds any policy making regarding scientists in national agricultural research programmes, it also makes it difficult to assess the needs and problems local rice breeders face around the world.MethodsA global online survey was conducted reaching 189 rice breeders from 51 rice-growing countries around the world. The questionnaire was structured according to an adoption framework we proposed from the literature. We specifically investigated their attitudes to adopting an alternative breeding method called rapid generation advance (RGA) (also known as single seed descent). To provide some historical perspective, we compare our results with those reported by Hargrove (Rice breeders in Asia: a ten-country survey of their backgrounds, attitudes, and use of genetic materials, 1978), the only published survey on rice breeders.ResultsOverall, rice breeders are highly educated and have a long experience with their main breeding method. However, a gender gap with respect to education seems to persist. Large variation in resources (staff, land and budget) was observed with a small number of resource-rich institutes and a large number of resource-poor institutes. Most rice breeders are focused on breeding for irrigated conditions. Most breeders have a relatively high degree of risk taking and time preference towards shorter breeding cycles. The majority of breeders are aware of RGA and its benefits with more than half having observed RGA in practice. Finally, breeders are confident in the RGA technique and estimate its resource savings to be substantial.ConclusionsBreeders’ willingness to adopt RGA was remarkably high. Surprisingly, adoption of RGA remains low (4% as main method). This may suggest that the benefits of using the RGA method still need to be further demonstrated in rice breeding. Our results could be useful to develop targeted extension material or interventions for implementing new technologies, which could be useful to high-level agricultural managers, international research centres and aid agencies.