In the spring of 2019 I was approached by one of the major TV broadcasting companies in Denmark - TV2 Denmark. They were looking for someone to make a system that would detect when a person wearing a suit was touched in very specific places. The suit was to be used in a series of social experiments in which TV2 wanted to investigate to what extent involuntary groping is an provaling issue in Danish clubs and bars. In order to accommodate this I designed, built and programmed a suit with capacitive sensors on the areas of the body relevant for this experiment, a wireless data transferring system and a browser based real time visualization application.



Working principle

The system works by utilizing much of the functionality of the popular ESP32 microcontroller, a high capacity lithium battery and a WiFi extending antenna. First the system utilizes 9 of the built in capacitive touch pins on the ESP32 corresponding to each of the sensing areas (breasts, hips, stomach, thighs, butt). The MCU then filters and processes the input from each sensor pin and then sends a small data packets containing the results wirelessly to a receiving access point and thus network.




When the wireless access point receives the data this is then being relayed to a MQTT broker running on the network. From here it is being visualized in a browser based application running on a local server to which any client on the network can gain access.

In short, when the input value of one of the sensors exceeds a certain threshold data about what sensor was touched is being wirelessly send from the suit to a network on which an application registers and visualizes what and when parts of the body was touched.




Creation

Since TV2 required for the suit to be both flexible and discreet I had to find totally new ways achieve this while also guaranteeing stability of the sensor inputs to avoid false positives. TV2 wanted the wearer of the suit to be able to move and dance naturally as well as making the suit so discreet that nobody would suspect that something unusual was going on while interacting with the wearer. From prior experiments I was sure that capacitive touch sensors was the technology to go with, however, I had to find a material that allowed me to get stable readings on a stretchy and moving surface. Therefore, I tested both copper tape and carbon spray on different types of stretchy textiles before settling on EMF blocking fabric as the material for the sensors glued onto a lycra suit.


After prototyping for months I was finally ready to put everything I'd learned together in a fully functional touch detection suit.