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Wearable & Implantable electronics Electronic patch increases therapy adherence TBy Wim De Geest and Bram De Muer oday, few patients accurately adhere to their medication prescriptions. This poor adherence to medication was reported by WHO back in 2003 to result in increased morbidity and death and was estimated to incur annual costs of approximately $100 billion. Moreover, the effect of this limited therapy adherence affects all players in the healthcare sector because it has a large impact on treatment outcomes. Several factors can contribute to a lack of therapy adherence, but most often, despite the many reminder systems currently available, patients simply forget to take their medication. An extensive review conducted by the World Health Organization (WHO) concluded that improving adherence has a much larger impact on overall global health than any other improvement of a specific medical treatment. In 64% of the cases, forgetfulness is the major reason for therapy non-adherence. Current tools to help improve adherence for prescribed medication, and more specifically in the cases where non-adherence is a matter of forgetfulness, have clear disadvantages including their size, complexity of use, impact on patient privacy and relatively limited effectiveness. A wearable transdermal reminder The need for an innovative, cost-effective and large scale deployable medication reminder system is answered by TheraSolve’s MemoPatch®. This new technology aims to be the simplest and most user-friendly “Stick & Play” reminder system, which supports and motivates patients in the real world, with day to day stressors and challenges to take their medication in a timely fashion. The MemoPatch consists of a small, flexible and self-adhesive dermal patch that gives its wearer a very clear and discreet ‘digital touch’ – an electrical stimulus when it is time to take a dose of medication or, more generally, to perform any prescribed healthpromoting activity. Dedicated microchip technology To the casual observer the patch looks and feels like a transdermal nicotine patch but includes complex mixed-signal electronics and power management technology to deliver a very different user experience. The patch needs to operate At the heart of the MemoPatch®, ICsense’s custom IC. for one entire week while delivering high-voltage, low energy reminder ‘pulses’ to the patient and accurately keeping track of time without expensive and bulky crystal-based timing generators. This was accomplished through the design of a custom IC. Pharmaceutical therapy bundled with Therasolve’s adherence technology. For the timing generator, ICsense has developed on-chip timers that eliminate all external components whilst still being able to achieve a timing accuracy of better than a 1000ppm. Since the timers are always on, power consumption has of necessity, to be minimized and only a few tens of microWatts (μW) is consumed. Triggered by the timer, the high-efficiency DC/DC converter and high-voltage driver circuit converts energy from a button cell power source into a series of high-voltage pulses large enough to be perceptible by the patient but non-irritating to them. In developing this solution, TheraSolve performed a range of elaborate user studies over several years to determine the right voltage, pulse shape and timing for the optimal ‘digital touch’ reminder. Although the specifics of the pulses used in the Memo- Patch are a closely guarded secret, pulse duration is in the order of 30 seconds. The ‘digital touch’ generated is distinctly noticeable – similar in nature to some of the emerging haptic technologies, without being distressing. The timing, voltage, power and shape of the pulses is fully programmable on chip and can be tailored in future to target patient profiles. However, in the initial production phase, an optimal pulse was identified and has been the focus of current pre-production standardization efforts. Drawing sufficient voltage and power from a single, high-resistance button cell battery, many times during a single week’s use has been a challenging system level design issue to solve. ICsense tackled the problem using state-of-the-art DC/DC converter techniques combined with clever duty cycling of the power generation system. Wim De Geest is the CEO and co-founder of TheraSolve – www. therasolve.com - He can be reached at wdg@therasolve.com Bram De Muer is CEO and co-founder of ICsense – www.icsense.com - He can be reached at demuer@icsense.com 28 Electronic Engineering Times Europe April 2015 www.electronics-eetimes.com


EETE APR 2015
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