29. Segue - What are Capacitive Sensors Anyway?

Since I've been facing trouble figuring out how to position the touch sensor in my silicone heart, I started researching how they worked. (Gonna admit that before this I just accepted that it worked and never thought about the how).

First place I looked was the manufacturer's website of this listing. I actually bought my sensor from a reseller based in Malaysia. 

Details found on the product listing. DFRobot actually has a wiki page for all its products, so that's what I checked out next.

Unfortunately this wiki page maily shows users how to wire things up and get started, instead of how the sensor works. 

Finally found this site which provided more technical information. 

"Capacitive touch sensors fall into two general categories: the mutual-capacitance configuration and the self-capacitance configuration. The former, in which the sensing capacitor is composed of two terminals that function as emitting and receiving electrodes, is preferred for touch-sensitive displays. The latter, in which one terminal of the sensing capacitor is connected to ground, is a straightforward approach that is suitable for a touch-sensitive button, slider, or wheel. This article presents the self-capacitance configuration. (Keim, 2016)"

"Proximity vs. Contact

The preceding discussion leads us to an interesting feature of capacitive “touch” sensing: a measurable change in capacitance can be generated not only by contact between the finger and the sensor but also by proximity between the finger and the sensor. I usually think of a touch-sensitive device as a replacement for a mechanical switch or button, but capacitive sensing technology actually introduces a new layer of functionality by allowing a system to determine the distance between a sensor and a finger." 

I think that my sensor is the grounded type, and I need to change how I slot it into the heart so that it can stay in place, not be triggered constantly. Right now I'm guessing the slight pressure from wedging the sensor between a cut in the silicone is causing the trigger. 

Heading to the electronics lab in a bit to sort out my LED stuff.

References:

DFRobot, n.d. Gravity: Digital Capacitive Touch Sensor For Arduino [Online] Available at: https://www.dfrobot.com/product-78.html [Accessed 1 May 2019]

DFRobot, n.d. DFRobot_Capacitive_Touch Sensor SKU DFR0030 [Online] Available at: https://wiki.dfrobot.com/DFRobot_Capacitive_Touch_Sensor_SKU_DFR0030 [Accessed 1 May 2019]

Keim, R. 2016. Introduction to Capacitive Touch Sensing [Online] All About Circuits. Available at: https://www.allaboutcircuits.com/technical-articles/introduction-to-capacitive-touch-sensing/ [Accessed 1 May 2019]