Why a sausage can do what your gloves cannot - Charles Wallace and Sajan Saini
How Sausages Helped Us Understand Touchscreens
The Cold Winter of 2010 and the Rise of Sausage Sales
- In 2010, South Korea faced an exceptionally cold winter, leading to difficulties in using smartphones while wearing gloves. This prompted people to use snack sausages instead, resulting in a 40% increase in sausage sales for one company.
Evolution of Touchscreen Technology
- The first touchscreen was invented in 1965 for British air traffic controllers but was too expensive and unwieldy for widespread adoption. Over decades, engineers developed various types of touchscreens, with resistive touchscreens becoming dominant.
Introduction of Capacitive Touchscreens
- Apple released the first iPhone in 2007, which utilized capacitive technology similar to early touchscreens. Today, capacitive and resistive are the two most common touchscreen types used in devices.
How Resistive Touchscreens Work
- A resistive touchscreen consists of two layers: a flexible top layer (usually plastic) and a rigid bottom layer (like glass), both coated with conductive material and separated by a thin gap. When pressure is applied, these layers connect to complete an electric circuit. This results in voltage changes that the device's software interprets as input. Although they can be unresponsive, they are cost-effective and durable for industrial applications.
Structure of Capacitive Touchscreens
- Modern smartphone screens typically have a protective glass exterior over an LCD screen with several sheets between them. One sheet contains transparent conductive lines carrying alternating current arranged in a grid pattern at nodes where they intersect. These nodes store charge due to their capacitor-like function when electrons accumulate from the battery's flow through the lines.
Interaction Between Finger and Screen
- Capacitive touchscreens are user-friendly as they respond directly to finger touches without requiring force; human bodies conduct electricity well due to their water content (about 60%). Impure water inside our bodies carries ions that facilitate this interaction when touching the screen, altering charge levels at specific nodes on the grid.
Limitations of Touchscreen Functionality
- Using smartphones with wet hands or gloves can disrupt electrical connections necessary for proper functionality—water may trigger multiple nodes simultaneously while gloves act as insulators preventing charge transfer altogether. This leads to issues like false inputs or no response from the device when trying to interact with it under such conditions.