Why a sausage can do what your gloves cannot - Charles Wallace and Sajan Saini

Summary

This video explores the evolution of touchscreen technology, highlighting the differences between resistive and capacitive screens. It delves into how capacitive touchscreens work by using conductive materials, electric fields, and the human body's natural conductivity. The video explains why gloves or wet hands hinder touchscreen usage and how quirky alternatives like sausages can work in place of a finger. Starting from the first touchscreen in 1965 to the iPhone’s breakthrough in 2007, the script offers a clear explanation of how modern touchscreens respond to touch and why they are more efficient than earlier versions.

Takeaways

• ❄️ South Korea's cold winter in 2010 led people to use snack sausages to activate smartphones because gloves were ineffective.
• 📱 Touchscreens work by detecting external input to complete an electric circuit.
• 🛫 The first touchscreen was invented in 1965 for British air traffic controllers but was too expensive for widespread use.
• 🔄 Over time, engineers developed different types of touchscreens, with resistive touchscreens dominating the market for a while.
• 🍏 In 2007, Apple revolutionized the market by introducing the iPhone with a capacitive touchscreen.
• 🔋 Capacitive and resistive touchscreens are the most common types today, both using electric current to detect touch.
• ⚡ Resistive touchscreens require pressure to complete the circuit, while capacitive ones use the body's natural conductivity.
• 💧 Capacitive touchscreens are more responsive but can struggle when hands are wet or gloved.
• 🧤 Gloves and water disrupt the connection needed for capacitive screens, but objects like sausages or banana peels can act as conductors.
• 🌍 The nodes on capacitive screens store electric charge, and the touch of a finger changes the charge, signaling the phone’s processor.

Q & A

What was the problem that led South Koreans to use snack sausages with their smartphones in 2010?

The particularly cold winter in South Korea made it difficult for people to activate their smartphones while wearing gloves, which are insulators and block the electrical connection required for capacitive touchscreens.

How does a resistive touchscreen function?

A resistive touchscreen has two layers coated with a conductive substance and separated by a thin gap. When pressure is applied, the two layers connect, completing an electric circuit. This change in voltage is detected by the software, allowing input to be registered.

What made capacitive touchscreens more popular after the iPhone’s release in 2007?

Capacitive touchscreens became more popular because they were easier to use than resistive touchscreens, allowing for direct interaction with the user's finger without the need for applied force. The iPhone’s success highlighted their advantages, leading to wider adoption.

What role does water inside the human body play in the use of capacitive touchscreens?

The water inside the human body contains ions that carry a net electrical charge, making the body a good conductor. When a finger touches the screen, it completes the circuit by interacting with the existing electric field, allowing the phone to register the touch.

Why do capacitive touchscreens not work well when wearing gloves?

Gloves act as insulators, preventing the electrical charge from flowing from your finger to the touchscreen. This interrupts the connection needed for the capacitive screen to detect the touch.

How does a capacitive touchscreen detect touch?

A capacitive touchscreen uses a grid of conductive lines that create electric fields at the intersection points, called nodes. When touched by a conductive object like a finger, it alters the charge at the affected nodes, and the screen's software detects and interprets the location of the touch.

What happens when water is splashed on a capacitive touchscreen?

Water on a capacitive touchscreen can cause multiple nodes to be triggered simultaneously, as the water interrupts the electric field and makes it seem like the screen is being touched in multiple places, which can lead to unintended inputs.

How do resistive and capacitive touchscreens differ in terms of durability and responsiveness?

Resistive touchscreens are generally more durable and cheaper, making them ideal for industrial or mass use, but they can be less responsive because they require physical pressure. Capacitive touchscreens, in contrast, are more sensitive and easier to use but can be less durable.

What materials are used in the construction of a resistive touchscreen?

Resistive touchscreens are made with a flexible top layer, typically plastic, and a rigid bottom layer, usually glass. Both layers are coated with a conductive substance and separated by a thin gap.

Why can objects like banana peels or sausages activate a capacitive touchscreen?

Objects like banana peels and certain processed meats can activate a capacitive touchscreen because they conduct electricity in a way similar to human fingers. They can serve as substitutes for fingers when the screen requires a conductive material to complete the electric circuit.

Outlines

00:00

📱 Sausage as Smartphone Stylus

In 2010, South Korea experienced a cold winter, leading people to use snack sausages to operate their smartphones, which saw a 40% rise in sausage sales. The question raised is why sausages could activate touchscreens while gloves couldn’t, introducing how touchscreens function.

🛠 Evolution of Touchscreen Technology

Touchscreens were first invented in 1965 for British air traffic control but were initially too cumbersome for widespread use. Over time, the technology evolved, with resistive touchscreens becoming prominent before Apple introduced the capacitive touchscreen in 2007, revolutionizing the market.

⚡ Capacitive and Resistive Touchscreen Mechanisms

Touchscreens today, mainly capacitive and resistive types, operate by completing electric circuits. Conductors allow electrons to flow, with resistive touchscreens requiring pressure to function. Capacitive touchscreens, on the other hand, are more user-friendly as they interact directly with conductive inputs like fingers.

🔌 How Resistive Touchscreens Work

A resistive touchscreen consists of two layers—one flexible (usually plastic) and one rigid (glass)—separated by a gap. Pressure causes the layers to connect, completing an electric circuit, and triggering a response. They are less responsive but affordable and durable, thus widely used in industrial settings.

📲 Capacitive Touchscreens Take Over

The iPhone's introduction of capacitive touchscreens revolutionized the industry, gradually replacing resistive screens. Capacitive screens are easier to use, consisting of layers of insulating glass, conductive materials, and nodes that store charge. They respond directly to touch without pressure.

💧 Water, Gloves, and Touchscreen Sensitivity

Capacitive touchscreens work by detecting the body's natural conductivity, which is enhanced by water in the body. However, using the screen with wet hands or gloves creates problems, as water can activate multiple nodes at once, and gloves act as insulators, blocking the flow of electricity.

🍌 Creative Alternatives for Touchscreen Activation

Objects like banana peels or processed meats can also activate capacitive touchscreens because they conduct electricity similarly to human fingers. This knowledge can be useful in unexpected situations where typical touch inputs like fingers or capacitive gloves are unavailable.

Keywords

💡Touchscreen

A touchscreen is an electronic display that responds to touch input, allowing users to interact with devices. In the video, two types of touchscreens are discussed: resistive and capacitive. The main theme of the video revolves around explaining how touchscreens work, specifically the capacitive screens used in smartphones today.

💡Resistive Touchscreen

A resistive touchscreen consists of two layers—one flexible and one rigid—that complete an electric circuit when pressed together. This type of touchscreen is described as less sensitive but more durable and cost-effective, making it popular in industrial use before being overtaken by capacitive screens in smartphones.

💡Capacitive Touchscreen

Capacitive touchscreens use the conductive properties of the human body to detect touch without requiring pressure. The video highlights that capacitive screens became widely popular after the release of the iPhone in 2007, and they function by detecting changes in the electric field caused by the touch of a conductor, like a finger.

💡Electric Circuit

An electric circuit is a path through which electrons flow. Both resistive and capacitive touchscreens rely on completing an electric circuit to detect touch. In resistive screens, pressure completes the circuit, while in capacitive screens, the human body's conductive nature alters the electric field to register a touch.

💡Conductor

A conductor is a material that allows electrons to flow easily, enabling the passage of an electric current. The video explains that the human body, made up of about 60% water containing ions, acts as a conductor for capacitive touchscreens, allowing smartphones to detect touch without physical pressure.

💡Insulator

An insulator is a material that does not allow electric current to pass easily. In the video, gloves and water are described as insulators that interrupt the connection between the screen and the finger, explaining why touchscreens often fail to work when wearing gloves or when wet.

💡Capacitance

Capacitance is the ability of a system to store an electric charge. Capacitive touchscreens get their name from the fact that the nodes on the screen behave like capacitors, storing electrical charges at different points. When touched, these charges change, which allows the device to detect where the touch occurred.

💡Node

Nodes are points on a capacitive touchscreen where horizontal and vertical conductive lines intersect, storing electrical charges. These nodes play a crucial role in detecting where a finger touches the screen by sensing changes in the electric field at specific intersections.

💡Ions

Ions are charged atoms or molecules, which contribute to the body's conductive properties. The video explains that the water in the human body is filled with ions, which makes our fingers capable of interacting with the electric field on capacitive screens, enabling touch detection.

💡Smartphone

A smartphone is a mobile device that combines cellular connectivity with advanced computing capabilities, typically featuring a touchscreen interface. The video discusses how the introduction of the iPhone in 2007, which utilized capacitive touchscreens, revolutionized the smartphone market by making touch interactions more intuitive and responsive.

Highlights

In 2010, South Korea experienced a particularly cold winter, and people used snack sausages to operate their smartphones, leading to a 40% increase in sausage sales.

The first touchscreen was invented in 1965 to help British air traffic controllers, but it was too expensive and unwieldy for widespread use.

Over the following decades, engineers developed and experimented with different kinds of touchscreens, eventually leading to the dominance of resistive touchscreens.

In 2007, Apple released the first iPhone, which used capacitive touchscreen technology, similar to the principle used in the first touchscreen.

Today, resistive and capacitive touchscreens are two of the most common types, both relying on external input to complete their electric circuits.

Resistive touchscreens consist of two layers: a flexible plastic top layer and a rigid glass bottom layer, separated by a small gap.

Resistive touchscreens require physical pressure to connect the layers and complete the circuit, which is detected by the machine’s software.

Capacitive touchscreens, as used in most smartphones today, are easier to use than resistive ones because they interact directly with the user's finger without requiring force.

Capacitive touchscreens consist of an insulating glass exterior, conductive sheets, and an LCD screen at the bottom to display images.

The touchscreen’s conductive sheets are arranged in rows and columns, forming a grid, with the nodes acting like capacitors to store charge.

Your body conducts electricity well due to its high water content, which is full of ions that allow it to interact with the electric field of the touchscreen.

Touching the screen with your finger changes the charge at the grid's nodes, which the phone’s microprocessor uses to detect the touch location.

Wet hands or gloves can interrupt the electrical connection, making it harder to use a capacitive touchscreen.

Water on the screen can trigger multiple nodes at once, causing the phone to behave as though touched in multiple places.

Objects like banana peels or processed meats, which conduct electricity similarly to fingers, can also activate a capacitive touchscreen.

Transcripts

In 2010, South Korea experienced a particularly cold winter.

People couldn't activate their smartphones while wearing gloves,

so they began wielding snack sausages—

causing one company to see a 40% rise in sausage sales.

So, what could sausages do that gloves couldn’t?

In other words, how do touchscreens actually work?

In 1965, the first ever touchscreen was invented

to help British air traffic controllers efficiently update flight plans.

However, the technology was too unwieldy and expensive for widespread use.

Over the following decades,

engineers further developed this technology

and experimented with alternative kinds of touchscreens.

Soon, resistive touchscreens dominated the market.

But then, in 2007, Apple released the first iPhone.

It was a breakthrough, yet it functioned using the same principle

as the first touchscreen: capacitance.

Nowadays, capacitive and resistive touchscreens

are two of the most common types.

Both use an external input to complete their electric circuits.

In conductive materials, electrons flow around atoms,

forming an electric current.

In contrast to insulators,

the electrons in conductors are weakly bound and flow easily.

A resistive touchscreen has two layers.

The top is a clear, flexible material— usually plastic—

while the bottom is something rigid, like glass.

These layers are coated with a conductive substance

and separated by a thin gap.

When something pushes hard enough, the layers connect,

completing the electric circuit.

This causes a change in voltage that the machine’s software reacts to.

Resistive touchscreens can be a little unresponsive,

but they're generally cheap and durable,

so they're favored for industrial or mass use.

A vast majority of the touchscreens produced in 2007 were resistive.

But in the years following the iPhone’s release,

most became capacitive.

Individual models vary, but smartphone touchscreens today

typically consist of a protective, insulating glass exterior

and an LCD screen at the bottom that produces the images you see.

Between the glass exterior and the LCD screen are several sheets.

One is lined with rows of a transparent, conductive material

that carry an alternating electric current.

A thin insulating layer separates these conductive lines from others

that are arranged as columns.

One on top of the other, the lines form a grid.

The points where they intersect are called nodes.

The phone's battery draws electrons along the first layer of lines,

and some electrons accumulate at every node,

creating a small electric field.

These screens are called capacitive touchscreens

because the nodes act like capacitors by storing charge.

They’re generally easier to use than resistive touchscreens

because they interact directly with your finger without the application of force.

Your body is a great conductor and is constantly transmitting electric currents.

Why? Because about 60% of you is water.

Now, while chemically pure water is an insulator,

most water is impure.

The water inside you is loaded with ions—

atoms or molecules that have a net electrical charge.

So when you click on an app, your finger functions like a third electrical line.

It interacts with the existing electric field,

which induces a weak electric current that travels through your finger

and eventually back into the phone.

This changes the amount of charge at the affected nodes.

And voltage measurements along the second layer of lines

tell the phone’s microprocessor which part of the screen is being touched.

However, if you try using a smartphone while your hands are wet or gloved,

you'll probably have some trouble.

Both interrupt the electrical connection between your finger and phone.

If water is splashed across the screen, it might trigger many underlying nodes,

and the phone could act like you’ve touched it in multiple places at once.

On the other hand, gloves are insulators, so the charge has nowhere to go.

Meanwhile, objects that conduct electricity about as well as your finger—

like banana peels and certain processed meats—

can all activate the screen—

knowledge that can come in clutch, when you’re in a pickle.