Talha Agcayazi

Soft, flexible 3D printed fibers for capacitive tactile sensing

This study presents our latest efforts towards developing a force sensor array by weaving 3D printed functionalized polymer fibers. Silicone was used as the base polymer and carbon fillers were used to impart electrical conductivity. Two “H”-shaped fiber cross-sections oriented orthogonally acted as a parallel plate capacitor and were used for detecting normal forces. In this article, we present the fabrication method of the unique “H”-shaped fiber cross-section along with the investigation of the relation between applied force and measured capacitance. We also report the sensor response to variation in temperature. The sensing crossover was found to have a stable mechanical and electrical response in the force range of 0–6 N and the performance of this soft sensor was not significantly affected by temperature.

A finger touch force detection method for textile based capacitive tactile sensor arrays

The use of touch-based technology to interact with electronic devices pre-dates modern day multi-touch technology and even the personal computer. It has recently been growing in popularity in wearable computing devices especially in the form of textile based tactile sensor. These sensors often target the detection of not only touch but also force applied. A significant problem arises here in differentiating inputs from an intended finger touch and just a bend of the sensor or other objects touching the sensor. In this work, we present our initial efforts to differentiate between a finger and an insulated object touch event on a custom textile based tactile sensor we developed before. Our experiments show that the two cases could be differentiated using the capacitance change of the neighboring cross-over points.

Wearable infant hydration monitor

Hydration monitoring, especially for infants, is generally limited to clinical environments. In these settings hydration is most often assessed using chemical analysis techniques. In this work we show our efforts to bring hydration monitoring to consumer market with a proof-of-concept wearable bio-impedance analyzer for infant hydration monitoring. While this technique is limited in that it cannot quantify total body water in an absolute sense, it is ideal for measuring changes to detect dehydration. Specifically, our sensor is implemented using an Analog Devices 5933 impedance analyzer. We combine this chip’s capabilities with an RFduino for Bluetooth communication with a smartphone. In our smartphone application we are able to monitor changes in hydration levels in real time. Finally, we test the capabilities of our system on two adult subjects. For all trials we measured a relative decrease in bio-impedance, and an increase in hydration.