[a] 1IntroductionInterest in real-timem onitoring of biochemical parameters using wearable/on-body sensors is ar apidly growing area of research [1],d ue in partt ot he convergence of interest of major economic sectors in applications based on new types of information. ICT companies like Apple and Googleare exploring ways to access biochemical information as am eans to move beyond the mature sensor technologies currently employed in exercise and sports APPs that track ausers location,body movements,temperature, energy expenditurea nd so on. These are typically based on physical transducers or imaging technologies embedded within wristbands or smart phones.H owever, employings imilar approaches that depend on time-series data to the domain of biochemical sensing is much more difficult, due to the complexc hallenges associated with access to representative samples (typically ab ody fluid) and the less predictable behavioro fc hemical sensors and biosensors over time.Since the exciting developments of the 1980s,t he application of biochemical sensing to real-timem onitoring of the human condition has scarcely advanced in terms of the performance of the sensors.T oday,t he use-model has almost entirely shifted awayf rom the early over-optimistic promise of implantable sensorst hat are in continuous contact with blood[ 2],t od evices sitedo utside the body that somehow can access ani nformation rich body fluid, like sweat [3] [4] or saliva [5].F or the past several decades,t he predominantu se model for health related diagnostics has been the disposable single-shot sensorc ombined with af inger prick access to blood samples.E xamples of use modelst hat involve real-time monitoring of body fluids (albeit over relatively short periods typically at most up to several days) include the integration of biosensors with contact lenses that can sample and report on the composition of ocular fluid,w hich is in turn reflective of the systemic blood composition [6].P erhapst he bestknown exampleo ft his is the collaborative ventureb etween Google and Novartis [7],b ased on Parviss work Abstract:Aplatform for harvesting and analysingt he sodium content of sweat in real time is presented. One is a watch format in which thes ampling and fluidic system,e lectrodes,c ircuitry and battery are arranged vertically,w hile in the other pod format, the electronics and battery components,a nd the fluidics electrodes are arranged horizontally.T he platformsa re designedt ob e securely attached to the skin using av elcros trap.S weat enters into the device through as ampling orifice and passes over solid-state sodium-selective and reference electrodes and into as torage area containing ah igh capacity adsorbent material. Thel iquid movement is entirely drivenb yc apillary action, and the flow rate through the device can be mediated through variation of the width of af luidic channel linking the electrodes to the sample storage area. Changing the width dimension through7 50, 500 and 250 mmp roduces flow rates of 38.20, 21.48 and 6.61 mL/min...

A wearable device for real-time monitoring of sodium levels in sweat is presented.

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In recent years, there has been significant progress in a number of sensing technologies related to on-body measurements, such as platforms for monitoring respiration, heart rate, location and movement. In these cases, the sensing element (s) are based on highly effective transducers that are increasingly integrated into garments such that they are becoming innocuous to the user. In contrast, the area of on-body chemical sensing remains highly under-developed. In this paper, we will address the significant challenges that are inhibiting the practical realisation of reliable chemical sensors and biosensors capable of generating accurate data in real time.