---
title: "The shocking history of capacitors"
canonical_url: "https://www.smoltek.com/shocking-history-of-capacitors/6449/"
date: 2023-12-24
author: "Thomas Barregren"
featured_image: "https://www.smoltek.com/wp-content/uploads/2023/12/santa-claus-experiments-with-electricity-jpg.webp"
categories:
  - name: "IR Blog Posts"
    url: "https://www.smoltek.com/category/ir-blog-posts.md"
tags:
  - name: "capacitors"
    url: "https://www.smoltek.com/topic/capacitors.md"
  - name: "history"
    url: "https://www.smoltek.com/topic/history.md"
  - name: "longread"
    url: "https://www.smoltek.com/topic/longread.md"
---

# The shocking history of capacitors

Like all capac­i­tors, ours orig­i­nates from the Ley­den jar, a glass bot­tle that can store elec­tri­cal charge. Ewald Georg von Kleist was the first to expe­ri­ence this abil­i­ty when he received a severe elec­tric shock in Octo­ber 1745. Pieter van Muss­chen­broek fol­lowed suit when he repeat­ed the exper­i­ment a few months lat­er, in Jan­u­ary 1746. This is the sto­ry about their shock­ing dis­cov­ery and the ear­ly devel­op­ment of the capac­i­tor – a  ground­break­ing com­po­nent that is ubiq­ui­tous in today’s electronics.

*If you pre­fer to lis­ten, you can click the play but­ton below to hear the arti­cle read aloud.*

## [](https://www.smoltek.com#the-early-history-of-electricity)The early history of electricity

The first known obser­va­tion of what we now call sta­t­ic elec­tric­i­ty was made by the Greek philoso­pher Thales of Mile­tus in 600 BC. He not­ed that amber, when rubbed against cloth, attracts light objects such as hairs. But it took more than two thou­sand years before any­one set out to explore this force.

Sir William Gilbert’s mag­num opus – *De Mag­nete*,  pub­lished in 1600 – con­tains some of the ear­li­est sys­tem­at­ic stud­ies of elec­tric­i­ty. He observed that sub­stances like glass, sul­fur, and dia­mond exhib­it­ed the same attrac­tion prop­er­ty as amber when rubbed. He called this an *elec­tric* force. The name is derived from the Greek word for amber.

Six decades lat­er, Otto von Guer­icke invent­ed a sim­ple machine to gen­er­ate sta­t­ic elec­tric­i­ty. His elec­tro­sta­t­ic gen­er­a­tor con­sist­ed of a ball of sul­fur cast on an iron axle, which, when pulled around and sub­ject­ed to fric­tion, gave off elec­tric charges, which man­i­fest­ed them­selves in sparks.

In 1705, Fran­cis Hauks­bee cre­at­ed an improved elec­tro­sta­t­ic gen­er­a­tor. It con­sists of a crank that rotates a large wheel from which a belt runs to a small­er wheel attached to an axle through a glass ball.

At the begin­ning of the 1730s, Charles François de Cis­ter­nay du Fay, also known as just Dufay, dis­cov­ered the exis­tence of two types of elec­tri­cal charges. He named them *vit­re­ous* and *resinous* after the mate­r­i­al he used to pro­duce them (glass and resin), but we call them *pos­i­tive* and *neg­a­tive*. Du Fay also noticed that two of the same repel and two of the oppo­site attract each oth­er. More­over, he dif­fer­en­ti­at­ed mate­ri­als in *electrics* and *non-electrics*, which are sim­i­lar but not iden­ti­cal to what we today call *con­duc­tors* and *insu­la­tors*.

![Copper engraving showing a man cranking a large wheel that transmits the motion to an axle with a glass ball that is held by a pair of hands.](https://www.smoltek.com/wp-content/uploads/2023/12/electrostatic-generator-1200x800.webp)

Fran­cis Hauksbee’s elec­tro­sta­t­ic generator.

## [](https://www.smoltek.com#igniting-alcohol)Igniting alcohol

In the fall of 1745, things sparked the explo­ration of electricity.

First up was Matthias Bose, who makes a name for him­self as a flam­boy­ant demon­stra­tor of exper­i­ments with sta­t­ic elec­tric­i­ty. In one of his most famous tricks, he ignites alco­hol float­ing on top of the water by gen­er­at­ing sta­t­ic elec­tric­i­ty, which he con­ducts through a met­al bar to the water.

His main con­tri­bu­tion to this sto­ry is the use of the met­al bar. He hung it hor­i­zon­tal­ly with one end above the Hauksbee’s rotat­ing glass ball. If the dis­tance is not too great, or if a met­al chain hangs from the met­al bar down to the glass ball with­out touch­ing it, the met­al bar will cap­ture sta­t­ic elec­tric­i­ty that can then be trans­ferred to some­thing else. In Bose’s show, it was the water with alco­hol on the surface.

## [](https://www.smoltek.com#zap)Zap!

Next up was Ewald Georg von Kleist. Inspired by Bose’s met­al bar, he tried to prove that elec­tric­i­ty can be under­stood as a fluid.

On Octo­ber 11, 1745, he filled a small med­i­cine bot­tle with alco­hol and closed it with a cork through which a nail was insert­ed. He then used a met­al bar to trans­fer sta­t­ic elec­tric­i­ty from an elec­tro­sta­t­ic gen­er­a­tor to the nail. In this way, he imag­ined that sta­t­ic elec­tric­i­ty was poured into the alcohol.

Von Kleist knew that the glass is an insu­la­tor. There­fore, he was con­vinced that sta­t­ic elec­tric­i­ty could be “cap­tured” and retained in the bottle.

He acci­den­tal­ly touched the nail.

Zap!

He was thrown across the room.

Von Kleist had received a strong elec­tric shock, prov­ing that he had cap­tured elec­tric­i­ty in the bot­tle (but not in the way he thought). In fact, he had cre­at­ed the world’s first capacitor.

## [](https://www.smoltek.com#disappointments)Disappointments

Von Kleist wrote about his exper­i­ment to sev­er­al oth­er elec­tri­cal exper­i­men­tal­ists. Some want­ed to try it themselves.

Warned by Von Kleist’s exam­ple, they kept their dis­tance when the exper­i­ment was repeat­ed. This proved unnec­es­sary, as the exper­i­ments failed, and noth­ing happened.

What a disappointment.

## [](https://www.smoltek.com#amateur-night)Amateur night

Von Kleist didn’t write to Anderas Cunaeus, a lawyer and ama­teur sci­en­tist. Yet Cunaeus came up with some­thing strik­ing­ly sim­i­lar. Maybe he had heard about Von Kleist’s exper­i­ment. Or not. Nev­er­the­less, he did a sim­i­lar exper­i­ment with house­hold items at his home.

The result?

Zap!

Cunaeus was out for two full days.

## [](https://www.smoltek.com#leiden-university-anno-domini-1746)Leiden University, anno Domini 1746

It is a cold evening in Jan­u­ary 1746. Snow is falling thick­ly in the court­yard of Lei­den Uni­ver­si­ty – the old­est in the Nether­lands. A few tardy stu­dents are cross­ing the court­yard from a lec­ture hall to the evening’s sup­per. They pass by the lab­o­ra­to­ry win­dow of Pieter van Musschenbroek.

Pro­fes­sor van Muss­chen­broek stands at the win­dow, think­ing of his friend, the lawyer Anderas Cunaeus, who has done what pro­fes­sion­als have failed to do – recre­ate von Kleist’s exper­i­ment from three months ago. Now, he will try to repeat the exper­i­ment himself.

He adjusts the chain so that its free end comes as close as pos­si­ble to the glass ball with­out touch­ing it.

Mean­while, one of his dis­ci­ples hangs a met­al wire over the oth­er end of the met­al rod. He then fills a glass jar with water.

They are now ready for the experiment.

## [](https://www.smoltek.com#setting-up-the-experiment)Setting up the experiment

While one of the stu­dents cranks the wheels of the elec­tro­sta­t­ic gen­er­a­tor, Pro­fes­sor van Muss­chen­broek takes the water-filled glass jar with his bare hands and holds it up so that the met­al wire is low­ered into the water.

Anoth­er stu­dent now takes clothes in his hands and holds them against the rotat­ing glass ball. The fric­tion between the glass and the cloths cre­ates sta­t­ic elec­tric­i­ty, pass­ing to the met­al bar through the met­al chain and fur­ther to the water through the met­al wire.

While stand­ing there, he thinks about Bose. He may be an assid­u­ous self-pro­mot­er, but stor­ing and trans­fer­ring sta­t­ic elec­tric­i­ty with a met­al bar was pret­ty clever.

![Kopparstick som visar van Musschenbroek setup.](https://www.smoltek.com/wp-content/uploads/2023/12/leyden-jar-1200x800.webp)

*The exper­i­ment set­up used by Pro­fes­sor van Musschenbroek.*

## [](https://www.smoltek.com#prove-up)Prove up

It’s time for the exper­i­ment itself. Pro­fes­sor van Muss­chen­broek reach­es out with his left hand to the met­al wire hang­ing into the glass jar he holds in his bare right hand.

Zap!

## [](https://www.smoltek.com#never-try-again)Never try again

On Jan­u­ary 20, 1746, Pro­fes­sor Muss­chen­broek wrote to his des­ig­nat­ed con­tact at the Paris Acad­e­my and told him about the exper­i­ment. He began his letter:

> I would like to tell you about a new but ter­ri­ble exper­i­ment, which I advise you nev­er to try your­self, nor would I, who have expe­ri­enced it and sur­vived by the grace of God, do it again for all the king­dom of France.
> 
> Pieter van Muss­chen­broek, Jan­u­ary 20, 1746

Abbé Jean-Antoine Nol­let con­firmed the exper­i­ment and then read Musschenbroek’s let­ter at a pub­lic meet­ing of the Paris Acad­e­my in April 1746. He named the elec­tri­cal stor­age device *Ley­den jar*, after Pro­fes­sor Musschenbroek’s university.

## [](https://www.smoltek.com#grounded)Grounded

Pro­fes­sor van Muss­chen­broek real­ized that a con­di­tion for the exper­i­ment to suc­ceed was that there was a con­duc­tor con­nect­ed to earth on the out­side of the glass jar.

In the cas­es of von Kleist, Cunaeus, and him­self, they were the con­duc­tor to earth, as they held the glass jar with their bare hands.

Those who failed had put down the glass bot­tle for fear of an elec­tric kiss. (In all hon­esty, they fol­lowed the best prac­tices of their time and delib­er­ate­ly ensured that the glass jar was not grounded).

## [](https://www.smoltek.com#the-novelty-is-spreading)The novelty is spreading

The Ley­den jar did not only shock Muss­chen­broek. Soci­ety was also shocked – both lit­er­al­ly and figuratively.

Self-pro­claimed “elec­tri­cians” held pub­lic demon­stra­tions where they gave sparkling shows and jolt­ed their audi­ence. Nat­ur­al philoso­phers elec­tro­cut­ed ani­mals to bet­ter under­stand this new force. Physi­cians applied elec­tric shocks to humans to cure var­i­ous ail­ments. And tech­nol­o­gists sent charges through wires over rivers and lakes to fig­ure out what it could be used for.

The news of Ley­den jar’s abil­i­ty to store elec­tri­cal charge made its way across the pond to what, for a few more years, would only be referred to as the Amer­i­can Colonies. There, Ben­jamin Franklin exper­i­ment­ed with Ley­den jars.

## [](https://www.smoltek.com#is-water-necessary)Is water necessary?

It is 1748, and we are at the home of Ben­jamin Franklin in Philadel­phia. He has just filled a Ley­den jar with charge and put it on a glass insulator.

With a look of deter­mi­na­tion, he begins his experiment.

Franklin pulls out the cork of the jar and lifts it with the wire through it. He grasps the bot­tle with one hand, and brings a fin­ger of the oth­er hand near its mouth. A strong spark comes from the water, as painful as if he had touched the wire before remov­ing it. It con­vinces Franklin that the elec­tric charge is not in the wire. It is still in the jar.

He pours water from the charged jar into an emp­ty sec­ond jar. The sec­ond jar shows no sign of elec­tric charge. Thus, the elec­tric charge must remain in the now emp­ty first jar.

“What the frock!” Franklin exclaims.

He reach­es for the teapot con­tain­ing fresh, unelec­tri­fied water and pours new water into the first jar. Test­ing it again, he finds it still capa­ble of giv­ing him a jolt.

He lat­er writes:

> Thus the whole Force of the Bot­tle and Pow­er of giv­ing a Shock, is in the Glass itself; the Non-electrics in Con­tact with the two Sur­faces serv­ing only to give and receive to and from the sev­er­al Parts of the Glass; that is, to give on one Side, and take away from the other.
> 
> Ben­jamin Franklin

## [](https://www.smoltek.com#does-the-shape-matter)Does the shape matter?

Franklin now asked whether the shape of the jar is cru­cial to its abil­i­ty to store charge.

He took a piece of win­dow glass and put it in his hand to test this. On top of it, he then puts a plate of lead that he had electrified.

Now comes the test itself: He puts a fin­ger to the plate. Zap! There was a spark and shock. In oth­er words, the shape doesn’t matter.

## [](https://www.smoltek.com#where-is-the-charge-stored)Where is the charge stored?

But where is the charge stored? On the glass? Or on the hand and the lead plate in con­tact with the glass?

Franklin placed a piece of win­dow glass between two lead plates to find out. The whole stack rests in his hand while he elec­tri­fies the top plate.

He then sep­a­rates the parts. The glass plate gave off tiny sting­ing sparks when he touched it. He could feel this in many places on the glass sur­face. He also notes that there are no charges in the lead plates. Final­ly, he returned the glass between the lead plates.

Now, the moment of truth: Franklin grabs both lead plates. Zap! A strong jolt showed that the charge was still there.

From this exper­i­ment, Franklin con­cludes that the elec­tric charge was on the glass and that the lead plates only served to bring the charge to or from its surface.

## [](https://www.smoltek.com#not-first)Not first

Franklin was not the first to dis­cov­er that water is unnec­es­sary and a glass plate works just as well as a glass jar to hold a charge. John Bevis had already demon­strat­ed this in the same year. How­ev­er, Franklin did not find out until later.

But unlike Bevis, who thought that the charge was in the met­al in touch with the glass plate, Franklin proved that the charge is actu­al­ly on the sur­face of the glass.

## [](https://www.smoltek.com#positive-is-lack-of-negative)Positive is lack of negative

More­over, Franklin also fig­ured out that there are not two types of charges, as du Fay had stat­ed almost two decades ear­li­er, but only one charge: the neg­a­tive one. A pos­i­tive charge aris­es when a neg­a­tive charge is removed.

In oth­er words, instead of see­ing pos­i­tive and neg­a­tive as two sep­a­rate enti­ties, Franklin viewed them as two states: the pres­ence of a neg­a­tive charge and the absence of it.

With these insights, gained just a few years after the dis­cov­ery of the Ley­den jar, it was now pos­si­ble to explain what hap­pened on that snowy win­ter evening when Pro­fes­sor van Muss­chen­broek had him­self electrified.

## [](https://www.smoltek.com#no-escape)No escape

The fric­tion against the glass ball gen­er­ates pos­i­tive charges. These are passed through the chain, bar, and wire into the water.

Since equal charges repel each oth­er, the pos­i­tive charges are pushed against the inside of the wall of the glass jar. Since the glass is an insu­la­tor, the charges can­not escape the jar.

## [](https://www.smoltek.com#redistribution)Redistribution

But the force with which charges repel equal charges and attract oppo­site charges isn’t stopped by an insu­la­tor. There­fore, the pos­i­tive charges inside the glass jar repel neg­a­tive pos­i­tive out­side the glass and attract neg­a­tive charges.

In its nat­ur­al state, the glass’s exte­ri­or has an equal mix of pos­i­tive and neg­a­tive charges. How­ev­er, the pos­i­tive charges inside the glass repel the exter­nal pos­i­tive charges, redis­trib­ut­ing them away from the sur­face while attract­ing neg­a­tive charges clos­er, con­cen­trat­ing them.

This process requires a ground path for the dis­placed pos­i­tive charges. This is where the hand becomes cru­cial, act­ing as a con­duc­tor to com­plete the cir­cuit and allow these charges to reach the ground through the experimentalist’s body.

## [](https://www.smoltek.com#storage)Storage

As the pos­i­tive charges in the jar grow, so does the resis­tance that new­ly added pos­i­tive charges must over­come. Even­tu­al­ly, the jar reach­es its max­i­mum charge capac­i­ty. There are a large num­ber of pos­i­tive charges on the inside of the glass and an equal num­ber of neg­a­tive charges on the out­side of the glass.

The charges remain as long as there is no way for the pos­i­tive charges to get to the neg­a­tive ones. So you could say that von Kleist was right – the jar stores charge, but not in the liq­uid, as he thought, but on the out­side and inside of the jar.

But as soon as there is an oppor­tu­ni­ty for the pos­i­tive charges to get to the neg­a­tive ones, they will take it. This is what hap­pened to von Kleist, Cunaeus, and Pro­fes­sor van Muss­chen­broek when they touched the nail or chain that was in con­tact with the water when they held the jar. The pos­i­tive charges rushed through their poor bod­ies – from the hand touch­ing the nail or chain to the hand hold­ing the jar. Zap!

## [](https://www.smoltek.com#caveat)Caveat

The above is a mod­ern descrip­tion of how a Ley­den jar works, using knowl­edge from the mid-18th cen­tu­ry. It is a sim­pli­fied view of, in par­tic­u­lar, what hap­pens on the sur­face and inside the glass wall.

It wasn’t until the 1910s that sci­en­tists had the knowl­edge to under­stand what hap­pens at the sub­atom­ic lev­el. It’s pret­ty damn inter­est­ing stuff, and the sto­ry lead­ing up to it is at least as excit­ing as the one we’ve heard so far. But telling this sto­ry would take us on too many wind­ing side roads, and dwelling on the capacitor’s inner work­ings is anoth­er arti­cle, so let’s fast-for­ward the time­line to the begin­ning of the 20th century.

## [](https://www.smoltek.com#fast-forward)Fast forward

Did you see what I just did? I used the word *capac­i­tor* in the con­text of the Ley­den jar. That’s because a Ley­den jar is actu­al­ly a capac­i­tor. That makes von Kleist’s med­i­cine bot­tle the very first ever made.

Fur­ther­more, when Franklin put met­al on both sides of a piece of win­dow glass, he cre­at­ed the world’s first *par­al­lel plate capac­i­tor*.

In fact, two par­al­lel plates insu­lat­ed from each oth­er are the very essence of a capac­i­tor. The insu­la­tion does not need to be made with glass. It can be vac­u­um, air, or any mate­r­i­al that doesn’t allow charges to move across the gap between the two plates.

Some iso­la­tors, like glass, have the prop­er­ty that they increase the abil­i­ty of the capac­i­tor to store charge thanks to a phe­nom­e­non called *polar­iza­tion* (sub­ject of anoth­er arti­cle). Such an iso­la­tor is called a *dielec­tric*.

All this began to be under­stood in the 19th cen­tu­ry and led to the first mod­ern capacitor.

## [](https://www.smoltek.com#birth-of-the-modern-capacitor)Birth of the modern capacitor

The Ley­den jar is a high-volt­age capac­i­tor. With the devel­op­ment of teleg­ra­phy, tele­phones, and radio in the late 19th cen­tu­ry, there was a need for small­er capac­i­tors for low­er volt­ages. This accel­er­at­ed the pace of innovation.

The first mod­ern capac­i­tor was devel­oped by D. G. Fitzger­ald. It con­sist­ed of met­al foil with impreg­nat­ed paper as a dielec­tric. He patent­ed the solu­tion in 1876. *Paper capac­i­tors*, as they came to be known, were fur­ther devel­oped and wide­ly used through­out the 1950s when plas­tic film capac­i­tors began to appear.

## [](https://www.smoltek.com#variety-of-capacitors)Variety of capacitors

The first paper capac­i­tors were fol­lowed by a for­mi­da­ble explo­sion of dif­fer­ent types of capacitors:

- vari­eties of *elec­trolyt­ic capac­i­tors*, where one plate is replaced by an elec­trolyte, includ­ing *tan­ta­lum capac­i­tors* and *nio­bi­um capacitors*
- *mica capac­i­tors* with mica as the dielectric
- *ceram­ic capac­i­tors* with a ceram­ic mate­r­i­al as dielec­tric, includ­ing  *ceram­ic disc capac­i­tors* and *mul­ti­lay­er ceram­ic chip (MLCC)  capacitors*
- *film capac­i­tor* with plas­tic film as dielec­tric, includ­ing *PET-capac­i­tors* and *PTFE-capac­i­tors*

## [](https://www.smoltek.com#capacitors-for-the-future)Capacitors for the future

Cur­rent and future demands for extreme minia­tur­iza­tion or for ultra-reli­able and ultra-sta­ble ser­vice result in the devel­op­ment of new types of capacitors.

*Inte­grat­ed capac­i­tors* are capac­i­tors formed by appro­pri­ate met­al­liza­tion pat­terns on an iso­lat­ing sub­strate. These include *met­al-oxide-met­al (MOM) capac­i­tors*, *met­al-oxide-semi­con­duc­tor (MOS) capac­i­tors*, and *met­al-insu­la­tor-met­al (MIM) capac­i­tors*. Despite the name of these types of capac­i­tors, they can be encap­su­lat­ed and sold as reg­u­lar, although very tiny, capac­i­tors. Some­times, they are also called *sil­i­con capac­i­tors* since the sub­strate is usu­al­ly sil­i­con. Sil­i­con com­pounds can also be used as dielectrics.

*Deep trench capac­i­tors (DTCs)* are cre­at­ed on a semi­con­duc­tor sub­strate by cre­at­ing deep recess­es, called *trench­es*, to max­i­mize the sur­face area and capac­i­tance in a small foot­print. DTCs are also known as *trench sil­i­con capac­i­tors (TSC)* and *sil­i­con capac­i­tors (SiCap)*.

*Glass capac­i­tors* are mod­ern Ley­den jars. They con­sist of mul­ti­ple lay­ers of met­al inter­twined with glass, sim­i­lar to how MLCCs are built. They are used in the most extreme sit­u­a­tions. Glass capac­i­tors are the most durable capac­i­tors in all respects. For exam­ple, they can with­stand high dos­es of nuclear radi­a­tion and strong neu­tron radiation.

Note that the term sil­i­con capac­i­tors can be used for both inte­grat­ed capac­i­tors and deep trench capac­i­tors. Quite confusing.

## [](https://www.smoltek.com#cnf-mim-capacitors)CNF-MIM capacitors

Of course, we can’t write an arti­cle with­out talk­ing about our car­bon nanofiber fiber met­al-insu­la­tor-met­al (CNF-MIM) capacitor.

With­out going into detail, we can say that CNF-MIM capac­i­tors are pro­duced in much the same way as the inte­grat­ed capac­i­tors of the MIM type. You might have guessed this by the name.

How­ev­er, they dif­fer from MIM capac­i­tors in one fun­da­men­tal way where CNF-MIM capac­i­tors are more sim­i­lar to DTC. Both DTC and CNF-MIM capac­i­tors use nan­otech­nol­o­gy to increase the sur­face area. This is impor­tant because the abil­i­ty to store charges is direct­ly pro­por­tion­al to the area.

But the area can only increase so much for DTC; the sky’s the lim­it for CNF-MIM capac­i­tors (almost lit­er­al­ly). DTCs have trench­es that are lim­it­ed how deep they can go before the sub­strate becomes too brit­tle and breaks. CNF-MIM capac­i­tors, on the oth­er hand, build car­bon nanofibers on top of the substrate.

## [](https://www.smoltek.com#humbling-perspective)Humbling perspective

Pieter van Muss­chen­broek was not the first to dis­cov­er the Ley­den jar. Still, he was the one who made it known and sparked a flur­ry of research into the nature of elec­tric­i­ty. Elec­tric­i­ty was stud­ied fran­ti­cal­ly for the next hun­dred and six­ty years or so. It’s an incred­i­bly fas­ci­nat­ing sto­ry, but since we’re approach­ing this article’s end, we’ll leave it at that.

Fast for­ward to today, Smoltek is dri­ving the devel­op­ment of suc­ces­sors to the Ley­den jar. The his­tor­i­cal per­spec­tive makes us feel hum­ble. Sure, our CNF-MIM tech­nol­o­gy is a big step for­ward for capac­i­tors, but it has been pre­ced­ed by oth­er, more essen­tial steps made by oth­ers before us. We feel hap­py to be a small link at the end of this 275-year-long chain of dis­cov­ery and development.

Zap!