Body-worn sensor design: what do patients and clinicians want?

User preferences need to be taken into account in order to be able to design devices that will gain acceptance both in a clinical and home setting. Sensor systems become redundant if patients or clinicians do not want to work with them. The aim of this systematic review was to determine both patients' and clinicians' preferences for non-invasive body-worn sensor systems. A search for relevant articles and conference proceedings was performed using MEDLINE, EMBASE, Current Contents Connect, and EEEI explore. In total 843 papers were identified of which only 11 studies were deemed suitable for inclusion. A range of different clinically relevant user groups were included. The key user preferences were that a body-worn sensor system should be compact, embedded and simple to operate and maintain. It also should not affect daily behavior nor seek to directly replace a health care professional. It became apparent that despite the importance of user preferences, they are rarely considered and as such there is a lack of high-quality studies in this area. We therefore would like to encourage researchers to focus on the implications of user preferences when designing wearable sensor systems.

A novel method for determining ground-referenced contacts during stair ascent: comparing relative hip position to quiet standing hip height.

Stair climbing can be measured using body-fixed sensors, whereby the origin and axes of the coordinate system are fixed with respect to the geometry of a body segment. These sensors can be part of a portable system, which provides the possibility to collect data in complex real-life environments. However due to the fact that the sensors are body-fixed, difficulties in determining the ground-based parameters of stair ascent can occur. The purpose of this study is to present a new approach for determining initial contacts based on a multi-chain biomechanical model combined with a new analysis method, in which relative hip height is compared to hip height during normal standing. Initial contacts obtained from the proposed method were compared to those obtained using an optical tracking device. An average absolute timing difference ranging from 0.04 (SD + or - 0.03) to 0.06 (+ or - 0.03) s and a root mean square error ranging from 0.05 to 0.07 s were found between the two techniques. This shows that the new approach presented in this study can be used to accurately determine initial contacts during stair ascent using portable equipment.