OpenCapSense: A rapid prototyping toolkit for pervasive interaction using capacitive sensing

Abstract

Abstract-Capacitive sensing allows the creation of unobtrusive user interfaces that are based on measuring the proximity to objects or recognizing their dielectric properties. Combining the data of many sensors, applications such as in-the-air gesture recognition, location tracking or fluid-level sensing can be realized. We present OpenCapSense, a highly flexible opensource toolkit that enables researchers to implement new types of pervasive user interfaces with low effort. The toolkit offers a high temporal resolution with sensor update rates up to 1 kHz. The typical spatial resolution varies between one millimeter at close object proximity and around one centimeter at distances of 35 cm or above.

MoviBed - Sleep Analysis Using Capacitive Sensors

“…We plan to rebuild the prototype using the OpenCapSense capacitive proximity sensing toolkit, that provides higher precision compared to the CapToolKit used in the current iteration [15]. We expect that this allows us to more precisely distinguish different movements and in addition get an idea about respiratory movements that allows additional reasoning about the current sleep phase [16].…”

Capacitive near-field communication for ubiquitous interaction and perception

“…Higher voltages increase the displacement current and lead to a better performance. Bigger electrodes allow for better capacitive coupling [13] but also pick up more background noise. In our examples, electrode sizes vary from 1 cm 2 to 100 cm 2 .…”

“…The low surface conductivity of transparent or printed materials themselves decreases the performance of capacitive coupling applications only slightly [13]. This fact can also be transferred to capacitive communications and enables a designer to choose from a wide variety of materials with different properties.…”

“…In the domain of proximity sensing, capacitive coupling can be used for recognizing gestures [14,28], sensing user locations [29] or their activities [13,37]. Also, capacitive sensing was used in wearable devices to measure muscle contractions for activity recognition [4].…”

“…The approaches rarely transmit information, they rather use traditional capacitive sensing techniques. However, modulation approaches like codedivision multiple access or frequency-division multiple access can also be found in this domain [13,28]. In order to discern different ways a user touches an object, capacitive sensing technology such as swept-frequency capacitive sensing [15,25] or time-domain reflectometry [36] were employed.…”