Introduction With an estimated present global market of US$ 86.3 billion and expected annual increase around 7.9 % from now to 2020, sensors are nowadays one of the most ac- tive areas of research and technological developments [1] and a basic pillar of the emerging mobile health strategy that is expected to be revolutionizing healthcare in the near future. The biosensor and chemical sensor category is one of the most growing segment of this market, main- ly due to increased use for medical purposes. Wearable electrochemical sensors conform a particularly lourish- ing category that beneits from the improvements in mi- cro and nano fabrication of electrodes and instrumental components based on a range of new electrode materials (e.g. graphene). They are also expanding thanks to the widespread availability of advanced signal processing and management technologies on smartphones, tablets and similar portable devices. The aim of this contribution is to highlight the most outstanding recent progresses in the ield of wearable electrochemical sensors for decen- tralized bioanalysis and show some examples of research trends that will shape the sector and expand applicability ields in the near future. Wearable sensors in the context of the new mobile health ecosystem Wearable electronic sensing devices and technologies, such as heart rate monitors, smart watches, tracking de- vices, smart glasses, and so on, are experiencing a period of rapid growth. Fitness dedicated devices are reported to be the most mature market, but there is a clear trend to combined devices including embedded sensors that track and analyze physical activity for self-control of training and physical status [2]. Wearable technologies will also inluence future medical technology, affecting our health and itness decisions, redeining the doctor-patient re- lationship and reducing healthcare cost, as part of the expanding mobile health concept that is currently under planning and deployment by health authorities and medi- cal technology providers. There is an increasing focus on making healthcare more patient-centric so that patients can be empowered to manage their care improving life- styles, enabling remote treatment of chronic conditions and informing healthcare providers to make better clinical decisions [3]. This is particularly important for monitoring elderly patients or chronic diseases in home settings, espe- cially in remote locations or underdeveloped regions with limited or no access to conventional healthcare assistance. Speciic features of wearable electrochemical sen- sors Electrochemical sensors represent an important sub- class of chemical sensors that rely on the measurements of current, potential or charge at an electrode as ana- lytical signals, which can be related to chemical param- eters. Characteristics of electrochemical sensing devices include high sensitivity (down to the nanomolar levels) and selectivity, a wide linear range (typically 2-3 orders of magnitude), minimal space and power requirements, low-cost instrumentation, and a fast and cost effective response. So they are suitable for direct and reliable mon- itoring in harsh conditions, including a vast range of relevant applications in the ields of clinical, industrial, JOURNAL OF APPLIED BIOANALYSIS, July 2015, p. 68-71. http://dx.doi.org/10.17145/jab.15.011 (ISSN 2405-710X) Vol. 1, No. 3 Wearable electrochemical sensors: innovative tools for the emerging mobile health ecosystem Eduardo Pinilla-Gil Universidad de Extremadura, Departamento de Química Analítica, Badajoz, Spain (Received: 22 May 2015, Revised 27 May 2015, Accepted 27 May 2015) *Correspondence: University of Extremadura, Departamento de Química Analítica, Campus Universitario, Avda. de Elvas, s/n. 06006 Badajoz, Spain Phone/Fax: +34924289389. E-mail: epinilla@unex.es 68 EXPERT OPINION Keywords: wearable sensors, electrochemical sensors, noninvasive sensors, mobile health.