
The E-Meter (also electropsychometer and Hubbard Electrometer) is an electronic device used in
Scientology
Scientology is a set of beliefs and practices invented by the American author L. Ron Hubbard, and an associated movement. It is variously defined as a scam, a Scientology as a business, business, a cult, or a religion. Hubbard initially develo ...
that allegedly "registers emotional reactions". After claims by
L. Ron Hubbard that the procedures of
auditing
An audit is an "independent examination of financial information of any entity, whether profit oriented or not, irrespective of its size or legal form when such an examination is conducted with a view to express an opinion thereon." Auditing al ...
, which used the E-Meter, could help heal diseases, the E-Meter became the subject of litigation.
Since then, the
Church of Scientology
The Church of Scientology is a group of interconnected corporate entities and other organizations devoted to the practice, administration and dissemination of Scientology, which is variously defined as a cult, a business, or a new religiou ...
publishes disclaimers declaring that the E-Meter "by itself does nothing", is incapable of improving health, and is used solely for spiritual purposes.
History
Mathison
Volney Mathison built an
EDA meter based on a
Wheatstone bridge
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to prov ...
, a
vacuum tube
A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...
amplifier
An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...
, and a large
moving-coil meter that projected an image of the needle on the wall. He patented his device in 1954 as an ''electropsychometer'' or E-meter,
and it came to be known as the "Mathison Electropsychometer".
In Mathison's words, the E-meter "has a needle that swings back and forth across a scale when a patient holds on to two electrical contacts".
Mathison recorded in his book, ''Electropsychometry'', that the idea of the E-Meter came to him in 1950 while listening to a lecture by
L. Ron Hubbard:
and
Hubbard told of that encounter in a 1952 recorded lecture:
Mathison began working with L. Ron Hubbard in 1951
and that year filed application for his first E-meter patent
U.S. Patent 2,684,670 After the partnership broke up in 1954, Mathison continued improving his E-meters with additional patents (, ), marketing them through his own company and publications, retaining many of the concepts and terms from his time with Hubbard.
In a separate line of development, EDA monitors were incorporated in
polygraph
A polygraph, often incorrectly referred to as a lie detector test, is a pseudoscientific device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a ...
machines by
Leonarde Keeler. Rigorous testing of the polygraph has yielded mixed results, and some critics classify polygraph operation as a
pseudoscience
Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable cl ...
.
Hubbard
The E-meter was adopted for use in
Dianetics
Dianetics is a set of pseudoscientific ideas and practices regarding the human mind, which were invented in 1950 by science fiction writer L.Ron Hubbard. Dianetics was originally conceived as a form of psychological treatment, but was reje ...
and
Scientology
Scientology is a set of beliefs and practices invented by the American author L. Ron Hubbard, and an associated movement. It is variously defined as a scam, a Scientology as a business, business, a cult, or a religion. Hubbard initially develo ...
when Mathison collaborated with Hubbard in 1951.
Some sources say the E-meter was "developed by Volney Mathison following Hubbard's designs", or that Hubbard invented it.
Hubbard falsely claimed to be the inventor of the E-meter, a claim which is in keeping with the Scientology stance that Hubbard is the "source", or "the only originator of all Dianetics and Scientology material".
The E-meter was not part of the early days of Dianetics and Scientology. Auditing was composed of conversation and not led by a mechanical device. Hubbard introduced an E-meter prototype during the 1952 Philadelphia Doctorate Course but did not introduce his transistorized version until several years later. The E-meter became "the principal material artifact" of Dianetics and Scientology from the 1960s onward.
In the book, ''
L. Ron Hubbard, Messiah or Madman?'',
Bent Corydon wrote:
Though it seemed for a while that Scientology's more advanced techniques would serve without an E-meter, a few months later in May 1955, Hubbard wrote:
The Scientology meter was smaller, based on
transistors
A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electric power, power. It is one of the basic building blocks of modern electronics. It is composed of semicondu ...
rather than
vacuum tubes
A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...
, and powered by a low-voltage
rechargeable battery
A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prima ...
rather than
line voltage.
From then on, the E-meter was a required tool for Scientology ministers. The "Hubbard Mark II" E-meter was christened in 1960 and the Hubbard Mark III shortly after. On December 6, 1966, Hubbard won a patent on the Mark V version under the name "Hubbard Electropsychometer". Corydon wrote that the Hubbard E-meter was actually developed by Scientologists Don Breeding and Joe Wallis,
though the patent () does not list other developers.
The Scientology E-meter has been redesigned and re-patented several times since its first introduction to Dianetics (e.g.: , , ).
Earlier similar devices
Electrodermal activity
Electrodermal activity (EDA) is the property of the human body that causes continuous variation in the electrical characteristics of the skin. Historically, EDA has also been known as skin conductance, galvanic skin response (GSR), electroderm ...
meters were first developed in 1889 in Russia, and psychotherapists began using them as tools for therapy in the 1900s.
HTML version
Use in Scientology

E-meters are used by Scientology practitioners known as "
auditors
An audit is an "independent examination of financial information of any entity, whether profit oriented or not, irrespective of its size or legal form when such an examination is conducted with a view to express an opinion thereon." Auditing al ...
". Scientology materials refer to the subject as the "
preclear". The auditor gives the preclear a series of commands or questions while the preclear holds a pair of cylindrical
electrodes
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a variety ...
("cans") connected to the meter, and the auditor notes both the verbal response and the activity of the meter. Auditor training includes familiarization with a number of
characteristic needle movements, each with a specific significance. Religion scholar Dorthe Refslund Christensen describes the e-meter as "a technical device that could help the auditor locate engrams and areas of change when auditing a
preclear".
Scientology concepts associated with the E-meter and its use are regarded by the scientific and medical communities as
pseudoscience
Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable cl ...
, as the E-meter has never been subjected to
clinical trial
Clinical trials are prospective biomedical or behavioral research studies on human subject research, human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel v ...
s as a therapeutic tool.
Scientologists claim that in the hands of a trained operator, the meter can indicate whether a person has been relieved from the spiritual impediment of past experiences. In accordance with a 1974 federal court order, the Church of Scientology asserts that the E-meter is intended for use only in church-sanctioned auditing sessions; it is not a curative or medical device. The E-meters used by the Church were previously manufactured by Scientologists at their
Gold Base
Gold Base (also variously known as Gold, Golden Era Productions, Int Base or Int) is the ''de facto'' international headquarters of the Church of Scientology, located north of San Jacinto, California, United States, about from Los Angeles. The h ...
facility,
but were being manufactured in
Hong Kong
Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
and
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
as of 1998.
According to Hubbard, the E-meter is used by the operator for three vital functions:
# To determine what process to run and what to run it on.
# To observe how well the process is running.
# To know when the process should be stopped.
The Church claims that the E-meter can be used to assess the emotional charge of single words, whole sentences, and questions, as well as indicating the general state of the subject when the operator is not speaking. Few users of the E-meter claim that it does anything to the subject. To most, it does no more than suggest to the operator a change of mental, emotional, or autonomic nervous system activity.
New religious movement scholar Douglas Cowan writes that Scientologists cannot progress along
the Bridge to Total Freedom without an E-meter, and that Hubbard even told Scientologists to buy two E-meters, in the event that one of them fails to operate.
According to anthropologist Roy Rappaport, the E-meter is a ritual object, an object that "stand
indexically for something intangible".
Other uses
Similar devices have been used as research tools in many
human studies
''Human Studies'' is a quarterly peer-reviewed academic journal
An academic journal (or scholarly journal or scientific journal) is a periodical publication in which Scholarly method, scholarship relating to a particular academic discipline i ...
and as one of several components of the
Leonarde Keeler's
polygraph
A polygraph, often incorrectly referred to as a lie detector test, is a pseudoscientific device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a ...
(lie detector) system, which has been widely criticized as ineffective and
pseudoscientific
Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable cl ...
by legal experts and psychologists.
PDF version
EDA meters are used in both therapist-patient and
bio-feedback settings. EDA is one of the factors recorded by
polygraphs, and EDA meters are often used in
human studies
''Human Studies'' is a quarterly peer-reviewed academic journal
An academic journal (or scholarly journal or scientific journal) is a periodical publication in which Scholarly method, scholarship relating to a particular academic discipline i ...
to gauge
psychological
Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...
responses.
Description

Most prominent on the face of the e-meter is a display with a needle pointer. There are several dials and knobs, and modern e-meters have several LCD displays. All models have knobs for turning the device on, testing it, setting the sensitivity, and boosting the device. The primary control for the auditor is the tone arm (a rotating lever) which is held throughout auditing and operated by one hand while the auditor writes with their other hand. As the needle on the display moves off the right or left of the dial, the tone arm is used to bring the needle back on the dial. During an auditing session, the auditor writes down questions he has asked the preclear, the preclear's answers, and activity of the e-meter such as needle movements and tone arm settings
Electronics
One of E-meter's primary components is a
Wheatstone bridge
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to prov ...
, an electrical circuit configuration invented in 1833 that enables the detection of very small differences between two
electrical impedance
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of Electrical_resistance, resistance and Electrical_reactance, reactance in a electrical circuit, circuit.
Quantitatively, the impedan ...
s (in this case,
resistances). The E-meter is constructed so that one resistance is the subject's body and the other is a
rheostat
A potentiometer is a three-terminal (electronics), terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
...
controlled by the operator. A small voltage from the battery is applied to electrodes held in the subject's hands. As the electrical properties (electrodermal activity) of the subject's body change during the counseling,
the resulting changes in the small electric current are displayed in needle movements on a large analog panel meter. The dial face is without numbers because the absolute resistance in
ohm
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (1 ...
s is relatively unimportant, while the operator watches primarily for characteristic needle motions. The
voltage
Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...
applied to the electrodes is less than 1.5 V, and the
electric current
An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...
through the subject's body is less than a half a
milliampere.
In the Scientology E-meter, the large control, known as the "tone arm", adjusts the
meter bias, while a smaller one controls the
gain. The operator manipulates the tone arm to keep the needle near the center of the dial so its motion is easily observed. A simple E-meter powered by direct current, such as that used by the Scientologists and the like, displays several kinds of electrodermal activity (EDA) on the one dial without distinction, including changes in
resistance and
bioelectric potential. Researchers in
psychophysiology
Psychophysiology (from Greek , ''psȳkhē'', "breath, life, soul"; , ''physis'', "nature, origin"; and , '' -logia'') is the branch of psychology that is concerned with the physiological bases of psychological processes. While psychophysiolog ...
are also exploring
admittance
In electrical engineering, admittance is a measure of how easily a circuit or device will allow a current to flow. It is defined as the multiplicative inverse, reciprocal of Electrical impedance, impedance, analogous to how Electrical resistanc ...
and
impedance aspects of EDA that can be observed only with
alternating current
Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...
.
The E-Meter, measuring variations in electrodermal activity (which can be highly responsive to emotion
), functions on the same physiological data sources as one of the parts of the
polygraph
A polygraph, often incorrectly referred to as a lie detector test, is a pseudoscientific device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a ...
, or "
lie detector". According to Scientology doctrine, the resistance corresponds to the "mental mass and energy" of the subject's mind, which are claimed to change when the subject thinks of particular mental images (
engrams). One account tells about Hubbard using the E-meter to determine whether or not fruits can experience pain, as in his 1968 assertion that tomatoes "scream when sliced".
The traditional theory of EDA holds that skin resistance varies with the state of
sweat glands
Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...
in the skin. Sweating is controlled by the
sympathetic nervous system
The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...
. Because sweat contains
electrolyte
An electrolyte is a substance that conducts electricity through the movement of ions, but not through the movement of electrons. This includes most soluble Salt (chemistry), salts, acids, and Base (chemistry), bases, dissolved in a polar solven ...
s (salt, etc.), conductivity is increased when the sweat glands are activated. But some advocates argue that the meter responds more quickly than would be possible by the exudation and drying of sweat. They propose an additional mechanism termed the "Tarchanoff Response", through which the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...
of the brain affects the current directly. This phenomenon is not completely understood, and further research needs to be performed.
Legal issues
United States
The medical establishment had been watching Hubbard's enterprises since 1951, when the
New Jersey State Board of Medical Examiners prosecuted the Hubbard Dianetic Research Foundation (
Elizabeth, New Jersey
Elizabeth is a City (New Jersey), city in and the county seat of Union County, New Jersey, Union County, in the U.S. state of New Jersey.[Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...]
(FDA) seized and destroyed 21,000
Dianazene tablets from Hubbard's
Distribution Center Inc., charging that they were falsely labeled as a treatment for radiation sickness.
On January 4, 1963, in service of an FDA complaint, more than 100
US marshals and deputized
longshoremen with drawn guns
raided the
Founding Church of Scientology in Washington, D.C., and confiscated more than three tons of property, including 5,000 books, 2,900 booklets, and several hundred E-meters.
The FDA accused the Church of making false medical claims that the E-meters could treat physical and
mental illness
A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
es. The FDA also charged that the meters did not bear adequate directions for treating the conditions for which they were recommended.
The Church claimed that they had not written any publication that the E-meter could or would heal anything and sued to get the property back. Years of litigation ensued. In the first trial beginning on April 3, 1967, the jury found that the Church misrepresented the E-meter, and the judge ordered the confiscated materials destroyed.
However, in 1969 the
US Court of Appeals for the District of Columbia reversed the verdict; the Church, it said, had made substantial showing that Scientology is a religion and the government had done nothing to rebut the claim.
The US Court of Appeals wrote:
Having found that Scientology was a religion, the Court wrote that the government was forbidden by the
First Amendment
First most commonly refers to:
* First, the ordinal form of the number 1
First or 1st may also refer to:
Acronyms
* Faint Images of the Radio Sky at Twenty-Centimeters, an astronomical survey carried out by the Very Large Array
* Far Infrared a ...
to the
Constitution
A constitution is the aggregate of fundamental principles or established precedents that constitute the legal basis of a polity, organization or other type of entity, and commonly determines how that entity is to be governed.
When these pri ...
to rule on the truth or falsity of the Church's doctrines and interfere with its practices, provided the claims are not manifestly insincere and the practices are reasonably harmless.
The Court ordered a new trial with the mandate that the trial court could not forbid auditing, use of the E-meter, or purveyance of the literature within a religious context. The FDA appealed the decision, but in 1969, the
US Supreme Court
The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all Federal tribunals in the United States, U.S. federal court cases, and over Stat ...
declined to review the case, commenting only that "Scientology meets the ''prima facie'' test of religion". In his 1973 judgment, District Court Judge
Gerhard Gesell ruled that:Unable to do more under the mandate from the Court of Appeals, Judge Gesell ordered all the property to be returned to the Church, and thereafter, the E-meter may be used only in "''bona fide'' religious counseling". All meters and referring literature must include a label disclaiming any medical benefits:
The church adopted a modified version of that statement, which it still invokes in connection with the E-meter. The current statement reads:
Judge Gesell also ordered the Church to pay all the government's legal fees and warehousing costs for the confiscated property for the nine years of litigation. He also required the church to pay the salaries and travel expenses of FDA agents who might, from time to time, inspect for compliance with the court's order. The raid was ruled illegal, but the government retained copies of the documents.
Sweden
In 1979, a court forbade calling the E-meter "an invaluable aid to measuring man's mental state and changes in it" in an advertisement. The prohibition was upheld by the
European Commission of Human Rights
The European Commission of Human Rights was a special body of the Council of Europe.
From 1954 to the 1998 entry into force of European Convention on Human Rights#Protocol 11, Protocol 11 to the European Convention on Human Rights, individuals d ...
in case ''
X. and Church of Scientology v. Sweden''.
France
In October 2009, a three-judge panel at the Correctional Court in Paris, convicted the church and six of its members of organized fraud. The Court's decision followed a three-week trial, where two plaintiffs alleged they were defrauded by the organization. One plaintiff's complaint involved the use of an E-Meter by Scientologists with medical implications. This plaintiff claimed that, after being audited with the device, she was encouraged to pay tens of thousands of euros for vitamins, books, and courses to improve her condition. She argued that amounted to fraud. The Court agreed, and the ruling was upheld on appeal in 2013. See .
Australia
In 1964, the government of
Victoria, Australia
Victoria, commonly abbreviated as Vic, is a state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of ; the second-most-populated state (after New South Wales), with a population of over 7 million; ...
, held a Board of Inquiry into Scientology which returned its findings in a document colloquially known as the
Anderson Report. Psychiatrist Ian Holland Martin, honorary federal secretary of the
Australian and New Zealand College of Psychiatrists, gave evidence that the E-Meter "used for Scientology" was a "psycho-galvano-meter" and was "dangerous in unqualified hands".
He said that if the E-meter "was suggested to possess mysterious powers" to someone who did not understand that it had "been thoroughly discredited as a lie detector" then "that person would be suggestible to ideas foisted on him by the operator".
The final report of the inquiry stated that the E-meter enabled Scientology
In 1965, Victoria banned the use of the E-meter without a license, with Western Australia and South Australia following suit. In 1969, the High Court of Western Australia ruled the ban illegal. South Australia repealed its law in 1973, and Victoria repealed it in 1982. In 1983, the High Court of Australia ruled that Scientology was a religion and as such had the same rights and protections.
Scientology beliefs and theories
Within the Church of Scientology, the early psychoanalysts are credited with first use of the E-meter.
Hubbard credited Mathison with recreating the E-meter and bringing him the first model for use in Dianetics.
Hubbard set out his
theory
A theory is a systematic and rational form of abstract thinking about a phenomenon, or the conclusions derived from such thinking. It involves contemplative and logical reasoning, often supported by processes such as observation, experimentation, ...
of how the E-meter works in his book ''Understanding the E-Meter'':
Hubbard claimed that this "mental mass" has the same physical characteristics, including weight, as
mass
Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...
as commonly understood by lay persons:
This text in ''Understanding the E-Meter'' is accompanied by three drawings. The first shows a man standing on a weighing scale, which reflects a weight of "150" (the units are not given). The next shows the man on the same scale, weighed down under a burden of "Mental Image Pictures", and the scale indicates a weight of "180". The last picture shows the man standing upright on the scale, now unburdened by "Mental Image Pictures" and with a smile on his face, while the scale again indicates a weight of "148".
Bob Thomas, senior executive of the church in the early 1970s, gave a prosaic description.
See also
*
Auditing (Scientology)
Auditing, also known as processing, is the core practice of Scientology. Scientologists believe that the role of auditing is to improve a person's abilities and to reduce or eliminate their neuroses. The Scientologist is asked questions about ...
*
Biofeedback
Biofeedback is the technique of gaining greater awareness of many physiology, physiological functions of one's own body by using Electronics, electronic or other instruments, and with a goal of being able to Manipulation (psychology), manipulate ...
*
Ohmmeter
An analog ohmmeter
An ohmmeter is an electrical instrument that measures electrical resistance (the opposition offered by a circuit or component to the flow of electric current). Multi-meters also function as ohmmeters when in resistance-meas ...
*
Thought identification
Notes
References
External links
''Scientology Today: What is the E-Meter and how does it work?'' official
Church of Scientology
The Church of Scientology is a group of interconnected corporate entities and other organizations devoted to the practice, administration and dissemination of Scientology, which is variously defined as a cult, a business, or a new religiou ...
description
''Secrets of Scientology: The E-Meter'' by
David S. Touretzky
* , filed by the
Church of Spiritual Technology on May 9, 1996, and published January 4, 2000
"New Religious Movements, Technology, and Science: The Conceptualization of the E-Meter in Scientology Teachings" Zygon: Journal of Religion and Science 51 (3):661-683 (2016) a thorough historical and critical study by scholar Stefano Bigliardi.
{{DEFAULTSORT:E-Meter
1951 introductions
Measuring instruments
Pseudoscience
Religious objects
Scientology beliefs and practices
Fraudulent detection devices