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Coil

A coil is a series of concentric loops or spirals, often formed by winding a flexible material around a cylindrical object. The term has applications across various fields. Coil may refer to:
  • In geometry: a helix or spiral shape (see Geometry section)
  • In engineering and technology: mechanical springs, electrical inductors, or other devices (see Engineering and Technology section)
  • In biology and medicine: coiled coil protein structures, the COIL gene, or medical tubing (see Biology and Medicine section)
  • In arts and entertainment: the experimental music group Coil (see Music under Arts and Entertainment), fictional characters, or literary expressions (see Arts and Entertainment section)
  • Other uses: as a surname, or organizations and brands (see Other Uses section)

Geometry

Helix

A helix is a curve in three-dimensional space that winds around a central axis at a constant angle, forming a smooth, continuous path along the surface of a cylinder. Geometrically, it can be defined as the locus of a point moving with uniform angular and linear velocity around a fixed axis, or equivalently, as the curve traced by the shortest path (geodesic) on a cylinder between two points not aligned vertically. The standard parametric equations for a right-circular helix centered on the z-axis are: \begin{align*} x &= r \cos t, \\ y &= r \sin t, \\ z &= c t, \end{align*} where r > 0 is the fixed radius of the cylinder, c is a constant determining the pitch (the vertical advance per full turn, equal to $2\pi c), and t is the parameter ranging over the reals. Key properties of the helix include its constant curvature \kappa = \frac{r}{r^2 + c^2} and constant torsion \tau = \frac{c}{r^2 + c^2}, which remain uniform along the curve regardless of the parameter value; these invariants characterize the helix as a space curve with steady bending and twisting. The ratio of curvature to torsion, \kappa / \tau = r / c, is also constant, distinguishing helices from more general curves by Lancret's theorem. Unlike a planar spiral, which lies flat in two dimensions and typically expands or contracts radially from a center point, a helix extends in three dimensions with a fixed radius and linear progression along the axis, though its projection onto a plane perpendicular to the axis resembles a circle rather than a spiral. The helical form was first practically realized in antiquity by the Greek mathematician Archimedes (c. 287–212 BCE), who invented the Archimedean screw—a device consisting of a helical surface within a cylinder—for irrigating fields and removing water from ships, marking an early application of helical geometry in engineering. In nature and technology, helices appear in introductory contexts such as the double helix configuration of DNA, where two intertwined strands form a stable right-handed helical structure essential to genetic encoding, and in screw threads, which follow a helical path to enable mechanical fastening and motion conversion.

Spiral

A spiral is a two-dimensional curve that winds around a fixed point, called the pole, with the radial distance from the pole to a point on the curve changing continuously as the polar angle increases or decreases. This curve is characterized by its radial expansion or contraction, distinguishing it from circular or elliptical paths where the distance remains constant. Common types include the Archimedean spiral and the logarithmic spiral, each defined by specific polar equations that govern their growth patterns. The Archimedean spiral follows the polar equation r = a + b \theta, where r is the radial distance, \theta is the polar angle in radians, and a and b are constants determining the initial radius and growth rate, respectively. Graphically, it produces a curve with evenly spaced arms, resembling a tightly wound coil where successive turns are separated by a constant distance $2\pi b, making it useful for uniform expansions in mathematical modeling. To derive its form, start with the polar coordinate system where points are specified by (r, \theta); plotting r linearly against \theta yields a spiral that increases steadily without acceleration, as the derivative dr/d\theta = b remains constant. In contrast, the logarithmic spiral is given by the polar equation r = a e^{b \theta}, where exponential growth ensures that the radius multiplies by a fixed factor over equal angular intervals. A key property is its self-similarity: scaling the curve by any factor and rotating it by a fixed angle superimposes it on itself, a consequence of the logarithmic term that preserves shape across scales. This self-similarity arises from the equation's derivation, where taking the natural logarithm yields \ln r = \ln a + b \theta, a linear relationship mirroring the spiral's equiangular nature, with the tangent line maintaining a constant angle \phi = \cot^{-1} b to the radius vector. Graphically, it appears as a smoothly expanding coil that accelerates outward, observed in natural growth patterns such as the chambers of nautilus shells, which approximate this form for efficient volume increase. Such spirals can extend conceptually to three-dimensional helices by incorporating an axial component.

Engineering and Technology

Mechanical Coils

Mechanical coils, particularly coil springs, are essential components in mechanical systems designed to store and release elastic potential energy, absorb shocks, and provide structural support. These devices operate based on the elastic deformation of materials, typically wound in a helical configuration to maximize efficiency in force application and energy storage. Unlike rigid structures, mechanical coils allow controlled flexibility, enabling applications from everyday machinery to heavy industrial operations. Coil springs are categorized into three primary types: compression springs, tension (or extension) springs, and torsion springs. Compression springs resist compressive forces by shortening under load and returning to their original length, commonly featuring open or closed ends for stability. Tension springs, conversely, elongate when pulled and contract to their initial form, often equipped with hooks or loops at the ends to facilitate attachment. Torsion springs provide resistance to angular deflection, storing energy through twisting motion around their axis, with legs extending from the body for mounting. Each type leverages the inherent elasticity of the material to perform its function, with the helical geometry ensuring uniform stress distribution. The behavior of these springs is governed by Hooke's law, which states that the restoring force F exerted by a spring is directly proportional to the displacement x from its equilibrium position, expressed as F = -kx, where k is the spring constant representing the stiffness of the spring. This linear relationship holds for small deformations within the elastic limit of the material. To derive Hooke's law from elastic potential energy, consider the potential energy U stored in the spring, given by the work done to deform it: U = \int_0^x F \, dx. Assuming the force is proportional to displacement, F = -kx, substitution yields U = \int_0^x (-k x') \, dx' = -\frac{1}{2} k x^2 (taking the negative sign into account for the restoring nature, the magnitude is U = \frac{1}{2} k x^2). Differentiating the potential energy with respect to position gives the force: F = -\frac{dU}{dx} = -k x, confirming Hooke's law as the gradient of the quadratic potential energy function. This derivation underscores the conservative nature of the spring force, where energy is reversibly stored and released without dissipation in ideal conditions. In applications, compression coil springs are widely used in automotive suspensions to absorb road impacts and maintain vehicle stability by supporting the chassis weight while damping vibrations. Torsion springs power clock mechanisms, such as in balance wheels or mainsprings, where they store energy to drive the escapement and regulate timekeeping through controlled unwinding. Coiled tubing, a specialized form of mechanical coil, consists of long, spooled metal pipes deployed in oil drilling for well interventions, enabling efficient circulation of fluids and tools without dismantling the production string. These examples highlight the versatility of mechanical coils in enhancing reliability and performance across scales. Materials for mechanical coils prioritize high yield strength, elasticity, and resistance to fatigue, with steel alloys such as music wire (high-carbon steel) and chrome-silicon steel being predominant for their ability to withstand repeated loading cycles. Fatigue limits, typically around 45-55% of the material's ultimate tensile strength for these alloys, dictate the operational lifespan, as exceeding them leads to crack initiation and failure under cyclic stress. Manufacturing often involves cold winding, where wire is coiled at room temperature on a mandrel using automated machinery, followed by heat treatment to set the microstructure and enhance durability; this process is preferred for springs under 3 inches in diameter to achieve precise tolerances and residual compressive stresses that improve fatigue resistance.

Electrical Coils

An electromagnetic coil consists of one or more loops of conductive wire wound around a , which generates a when passes through it. This stems from the by in 1820, who observed that a current-carrying wire deflects a nearby compass needle, demonstrating the link between electricity and magnetism. The magnetic field strength increases with the number of turns and the current, enabling controlled manipulation of magnetic forces in various devices. A key phenomenon associated with electromagnetic coils is induction, governed by Faraday's law, which states that a changing magnetic flux through the coil induces an electromotive force (emf). The induced emf \epsilon is given by \epsilon = -N \frac{d\Phi_B}{dt}, where N is the number of turns in the coil and \frac{d\Phi_B}{dt} is the rate of change of magnetic flux \Phi_B. This law, experimentally established by Michael Faraday in 1831, underpins the conversion of mechanical energy to electrical energy and vice versa in many systems. Common types of electrical coils include solenoids, inductors, ignition coils, and transformers. A solenoid is a tightly wound helical coil that produces a uniform magnetic field inside its core, with inductance L approximated by L = \mu_0 \frac{N^2 A}{l}, where \mu_0 is the permeability of free space, N is the number of turns, A is the cross-sectional area, and l is the length of the coil. Inductors store energy in magnetic fields to filter signals or store energy in circuits. Ignition coils, functioning as step-up transformers, amplify low-voltage battery power to high-voltage sparks for internal combustion engines. Transformers use paired coils to transfer electrical energy between circuits via mutual induction, enabling efficient voltage adjustment in power distribution. Electrical coils find widespread applications in motors and generators, where rotating coils interact with magnetic fields to produce torque or electrical output based on Faraday's law. In wireless charging systems, resonant inductive coupling between transmitter and receiver coils transfers power without physical connections, achieving efficiencies up to 90% over short distances for devices like electric vehicles. The historical evolution from Ørsted's foundational experiments led to practical inventions like the electromagnet by Joseph Henry in the 1830s, paving the way for modern electrical engineering advancements.

Other Technological Applications

In chemical laboratories, coiled condensers such as the Graham condenser utilize a coiled inner tube surrounded by a coolant jacket to efficiently cool and condense vapors during distillation processes. This design provides a larger surface area for heat transfer compared to straight-tube alternatives, allowing vapors from heated liquids to spiral downward while being cooled by circulating water, thereby preventing flooding and enhancing recovery of solvents. The coiled structure promotes turbulent flow, which improves condensation efficiency in applications like reflux and vacuum distillation. The chemical oxygen-iodine laser (COIL) represents a specialized high-energy laser system that employs chemical reactions to achieve population inversion and generate a near-infrared beam at 1.315 μm. Developed in 1978 at the U.S. Air Force Research Laboratory, COIL involves the excitation of iodine atoms through energy transfer from chemically produced singlet oxygen, enabling scalable power output without electrical discharge. By the early 1990s, prototypes reached 100 kW, demonstrating excellent beam quality and atmospheric transmittance suitable for directed-energy applications. Primarily pursued for military purposes since the late 1970s, COIL has been integrated into systems like the Airborne Laser (ABL) for missile defense and the Advanced Tactical Laser (ATL) for tactical engagements, with potential extensions to ground- and space-based platforms. In petroleum engineering, coiled tubing consists of continuous, flexible steel pipe spooled on a reel and deployed via a coiled tubing unit for downhole operations in oil and gas wells. This technology enables live-well interventions without requiring full workover rigs, facilitating tasks such as cleanouts of sand or scale using jetting tools, perforating with guns to initiate production, and conveying logging or plugging tools in high-angle wells. Additional applications include cement placement for zonal isolation, acid stimulation to enhance reservoir permeability, and coiled tubing drilling for directional wells, all while maintaining continuous circulation to minimize formation damage. Coiled tubing operations reduce mobilization time, personnel needs, and environmental footprint compared to jointed pipe methods, with typical lengths ranging from 2,000 to 30,000 feet.

Biology and Medicine

Coiled Coil Structures

A coiled coil is a found in proteins, consisting of two or more α-helices that wind around each other in a superhelical fashion, resembling the strands of a rope twisted together. This assembly is primarily stabilized by hydrophobic interactions between nonpolar residues at the helical interfaces, particularly at positions a and d of a characteristic heptad repeat sequence (abcdefg) along the helices. Coiled coils are ubiquitous in fibrous proteins, such as keratin, which forms structural filaments in hair and skin, and myosin, a key component of muscle fibers. The structural hallmark of many coiled coils, especially those involved in dimerization, is the leucine zipper motif, where leucine residues occupy the d positions of the heptad repeat, enabling tight packing and parallel or antiparallel alignment of the helices. This motif was first identified in DNA-binding proteins and confirmed to adopt a coiled-coil conformation through biophysical studies. Coiled coils exhibit evolutionary prevalence across eukaryotes, where they frequently mediate homodimer or heterodimer formation, comprising up to 10% of coding sequences in some proteomes and arising independently over a hundred times to support diverse oligomeric states. Functionally, coiled coils play critical roles in molecular processes, including muscle contraction, where the long coiled-coil tail of myosin heavy chains assembles into bipolar filaments that interact with actin to generate force. In gene regulation, they facilitate dimerization of transcription factors, such as GCN4 in yeast, allowing the basic regions adjacent to the zipper to bind DNA consensus sequences cooperatively. These structures have been elucidated primarily through X-ray crystallography, which revealed the parallel, two-stranded coiled-coil architecture of the GCN4 leucine zipper at atomic resolution, confirming the hydrophobic core and helical crossing angle. This motif builds upon the inherent geometry of individual α-helices, enhancing stability through interhelical packing. Recent advances as of 2025 include using coiled-coil fusions for cryo-EM structural determination of small proteins like kRasG12C and as scaffolds in drug delivery.

COIL Gene and Proteins

The COIL gene, located on the long arm of human chromosome 17 at cytogenetic band 17q22, spans approximately 11.5 kilobases and consists of seven exons. It encodes the 576-amino-acid protein coilin, a highly conserved marker and scaffolding component essential for the formation and maintenance of Cajal bodies (CBs) in the cell nucleus. Coilin was first identified in 1991 through the use of human autoimmune sera that specifically recognized nuclear foci, leading to the cloning and sequencing of the COIL cDNA, which revealed its expression across various tissues and cell types. Early ultrastructural and immunological studies in the 1990s confirmed coilin's localization to coiled bodies—later renamed Cajal bodies—and established its role as a diagnostic marker for these subnuclear organelles. Coilin functions primarily in the biogenesis and maturation of small nuclear ribonucleoproteins (snRNPs), which are critical for pre-mRNA splicing in eukaryotic cells. Within Cajal bodies, coilin concentrates snRNPs and associated factors, promoting efficient assembly steps such as trimethylguanosine capping of snRNAs and recycling of spliceosomal components. The protein's N-terminal domain facilitates multivalent interactions with other nuclear proteins, including the survival motor neuron (SMN) complex, while its central RG box and C-terminal regions support self-association and RNA binding. Coilin also contains a predicted coiled-coil domain (residues 290–321) that likely contributes to its structural integrity and interactions within the membraneless environment of Cajal bodies. Disruptions in coilin-mediated processes are linked to spinal muscular atrophy (SMA), a neurodegenerative disease primarily caused by mutations in the SMN1 gene on chromosome 5q13. SMN directly binds coilin via its Tudor-like domain, recruiting the SMN complex to Cajal bodies to facilitate snRNP maturation; reduced SMN levels in SMA patients impair this recruitment, leading to defective snRNP assembly and nuclear gems (SMN-rich foci) that fail to fully coalesce with Cajal bodies. Key studies from the early 2000s, including coilin knockout models in mice, demonstrated that while coilin is not essential for viability, its absence results in residual, dysfunctional Cajal bodies unable to properly recruit snRNPs or SMN, underscoring its role in nuclear organization and splicing efficiency. Ongoing research continues to explore coilin's phosphorylation and methylation as regulators of Cajal body dynamics, with implications for therapeutic targeting in SMA. As of 2024–2025, studies have identified new coilin interactors coordinating Cajal body assembly, roles in vertebrate innate immunity via microRNA production, and its prognostic significance in hepatocellular carcinoma, where high COIL expression correlates with poor overall survival.

Medical Devices

Intrauterine devices (IUDs), often referred to as coils in medical contexts, are small, T-shaped devices inserted into the uterus to provide long-acting reversible contraception. Copper IUDs, such as the ParaGard, release copper ions that create a spermicidal environment by impairing sperm motility and viability through a localized inflammatory response in the uterine cavity, preventing fertilization without affecting ovulation. These devices are hormone-free and effective for up to 10 years, with a typical-use failure rate of less than 1%, making them over 99% effective in preventing pregnancy. Hormonal IUDs, like those containing levonorgestrel (e.g., Mirena or Kyleena), release progestin that thickens cervical mucus to block sperm, thins the endometrial lining to inhibit implantation, and may suppress ovulation in some users, offering efficacy exceeding 99% and lasting 3 to 8 years depending on the formulation. The of IUDs traces back to early 20th-century inert devices like gut-wrapped Graefenberg , but iterations emerged in the 1960s with biologically inert models, such as the Lippes , designed to provoke a that alters the uterine to deter implantation. By the 1970s and 1980s, medicated incorporating improved and reduced side effects compared to earlier inert types, leading to widespread as a safe, reversible option. As of 2025, the U.S. FDA approved Miudella, a new low-dose copper IUD (175 mm²) effective for up to 3 years, offering a more flexible alternative to traditional copper devices. Safety profiles are favorable, with rare serious complications; expulsion occurs in approximately 2-10% of cases within the first year, higher in postpartum insertions (up to 17-28% immediately post-delivery), while uterine perforation affects fewer than 1 in 1,000 users. Endovascular coils represent another critical medical application, primarily used to treat intracranial aneurysms by occluding the aneurysm sac and promoting thrombus formation to prevent rupture and subarachnoid hemorrhage. These soft, platinum-wire devices are deployed via microcatheters inserted through femoral artery access, conforming to the aneurysm's helical shape for dense packing that isolates the sac from blood flow. The technique originated with the Guglielmi detachable coil (GDC) system, first clinically used on March 6, 1990, at UCLA, allowing controlled, electrolytically detachable placement to minimize migration risks. Since the 1990s, advancements like bioactive coatings have enhanced long-term occlusion rates, with studies showing complete aneurysm occlusion in 80-90% of cases and reduced rebleeding risk compared to untreated aneurysms, though recanalization occurs in 10-20% requiring retreatment. Complications, including thromboembolism or procedural perforation, affect 5-10% of patients but have declined with improved coil designs. As of 2024–2025, innovations include softer microcoils like Target Tetra for tiny aneurysms, bioactive MCP-1 coated coils for wound healing, and intrasaccular devices for complex cases, improving safety and efficacy.

Arts and Entertainment

Music

Coil was an English group formed in in 1982 by (born Geoffrey Rushton) as an initial that quickly evolved into a with his Peter "Sleazy" Christopherson, both former members of the post-industrial . The duo's departure from Psychic TV in early 1984 marked a pivotal shift, allowing Coil to pursue independent explorations in sound manipulation and thematic depth. Their music blended post-industrial noise, ambient textures, ritualistic elements, and occult-inspired motifs, often incorporating tape loops, synthesizers, and unconventional instrumentation to create immersive, otherworldly compositions. Key releases included the 1986 album Horse Rotorvator, a stark meditation on death and decay featuring tracks like "The Golden Section" that integrated Middle Eastern influences and stark percussion, and the 1999 double album Musick to Play in the Dark Vol. 1 and Vol. 2, which delved into dark ambient soundscapes with ethereal vocals and minimalist electronics, influencing later artists in neofolk and dark ambient genres. Coil's output spanned over 30 albums and numerous EPs until its dissolution following Balance's accidental death from a fall on November 13, 2004, at age 42; Christopherson announced the project's end after Balance's death and continued related work until his own death in 2010, with posthumous releases like The Ape of Naples (2005) and ongoing archival reissues and collections, including Black Antlers (2025) and Astral Disaster (Definitive Edition) (2025), emerging from existing recordings. This Mortal Coil was a short-lived but influential studio project initiated by 4AD Records founder Ivo Watts-Russell in 1983, functioning as a collective rather than a fixed band, with Watts-Russell and producer John Fryer as the core contributors enlisting guest musicians and vocalists from the label's roster. Active until 1991, it produced three albums of reinterpretations, primarily covers of classic songs reimagined through dream pop and gothic lenses, emphasizing emotional intimacy and atmospheric production. The debut, It'll End in Tears (1984), featured haunting renditions such as Cocteau Twins' Elizabeth Fraser and Robin Guthrie on a version of Big Star's "Kangaroo," alongside contributions from Dead Can Dance's Lisa Gerrard and Howard Devoto, establishing the project's signature melancholic sound that bridged post-punk and emerging shoegaze influences. Subsequent releases like Filigree & Shadow (1986) and Blood (1991) expanded this approach, incorporating original material and further collaborations, leaving a legacy in alternative music for its innovative songcraft and emotional resonance. Coil's innovations in post-industrial and ritual music extended beyond their catalog, shaping ambient and experimental scenes through their emphasis on sonic alchemy and taboo subjects, while This Mortal Coil's ethereal covers helped define 4AD's dream pop aesthetic in the 1980s.

Fictional Entities

In the G.I. Joe franchise, The Coil is depicted as a splinter faction of the Cobra organization, emerging as a fanatical covert group in the Devil's Due comic series published in the early 2000s. Led by figures like Tomax and Xamot, The Coil operates as an antagonist force, plotting against both G.I. Joe and Cobra leadership in storylines involving internal rebellions and ancient Cobra-La legends. In the web serial Worm by Wildbow, published from 2011 to 2013, Coil is the alias of Thomas Calvert, a parahuman supervillain classified as a Thinker with the ability to simulate and choose between two parallel timelines, effectively granting precognitive decision-making. As a crime lord in Brockton Bay, he manipulates criminal groups like the Undersiders for territorial control and larger schemes against authorities such as the PRT. In DC Comics, Coil appears as an elastic supervillain in two distinct continuities. On New Earth, he debuts in Superboy #40 (1983), created by the villainous Master (Robby Reed) and possessing contortionist abilities to extend and compress his body for combat and escape. In the Dakotaverse, another version emerges in Static #10 (1994) as a Bang Baby with similar elasticity powers, serving as a low-level antagonist in Milestone Media stories. Den-noh Coil (also known as Dennō Coil), a 2007 Japanese anime series produced by Madhouse, explores a near-future world where children use "Dennō Megane" augmented reality eyeglasses, referred to as "coils," to interact with virtual overlays in everyday life. The 26-episode story follows protagonist Yūko "Yasako" Okonogi as she uncovers mysteries involving disappearing children, virtual ghosts, and the technology's societal impacts in Daikoku City. The 2002 Star Trek novel Immortal Coil by Jeffrey Lang, part of the The Next Generation series, centers on Lieutenant Commander Data investigating the sabotage of a new Starfleet android, revealing historical secrets about artificial lifeforms and their creators across the Star Trek universe. The narrative delves into themes of android immortality and legacy, tying into Data's quest for humanity amid threats from rogue AIs. In the Pokémon franchise, Magnemite's Japanese name is "Coil" (コイル, Koiru), a direct reference to electromagnetic coils that inspired its design as a floating, magnetic Electric/Steel-type Pokémon introduced in Generation I. This nomenclature highlights its mechanical, coil-like body structure used for generating magnetic fields and levitation.

Idiomatic and Literary Uses

The phrase "mortal coil" originates from William Shakespeare's Hamlet (1603), specifically in Act 3, Scene 1, where Prince Hamlet contemplates suicide in his famous soliloquy: "For in that sleep of death what dreams may come / When we have shuffled off this mortal coil, / Must give us pause." Here, "mortal coil" symbolizes the earthly troubles, physical body, and turmoil of human life, with "shuffling off" representing death as a release from these burdens. The term "coil" evokes a sense of turbulent commotion or entanglement, drawing on Elizabethan usage to depict life's chaotic struggles. Philosophically, the interpreted as encapsulating existential dilemmas about mortality, the , and the of that prolongs , influencing thinkers who explore amid . In , it resonates with analyses of art's in and inner , as seen in Lev Vygotsky's of Hamlet as a for understanding emotional and the psyche's with oblivion. These interpretations underscore the 's depth, transforming a dramatic utterance into a lens for broader reflections on existence. In modern literature, "coil" serves as a motif for entanglement and inescapable fate, notably in Eric S. Nylund's Mortal Coils series (2009–2010), where the title alludes to Shakespeare's idiom while depicting protagonists ensnared in mythological family legacies and cosmic conflicts between celestial and infernal forces. This blending of ancient myth with contemporary family drama uses coils metaphorically to represent layered deceptions and hereditary burdens, emphasizing themes of identity and rebellion against predestined roles. The phrase's cultural impact persists in contemporary media, where it evokes struggles with mortality and destiny, often repurposed to highlight personal or societal reckonings with life's impermanence and ethical dilemmas. Its enduring presence in idioms and narratives reinforces Shakespeare's influence on discussions of fate, appearing in works that probe the tension between endurance and escape from existential entanglements.

Other Uses

Surname

The surname Coil is primarily a variant of the Irish surname Coyle, derived from the Gaelic Mac Giolla Chomhghaill, meaning "son of the devotee of St. Comgall," a 6th-century Irish saint. It also appears as an Americanized form of the German surname Geil. The name emerged through anglicization during periods of migration, particularly among Irish and Scottish families. Coil bearers are distributed worldwide, with approximately 2,905 individuals recorded (as of circa 2014), predominantly in North America where 97% reside. The United States hosts the highest concentration, with 2,775 bearers, followed by Canada (31) and Venezuela (41); in the US, the surname's prevalence increased 275% between 1880 and 2014. This growth traces to 19th-century immigration, with early records showing Coil families arriving in the US, UK, and Canada from the 1840s onward, often settling in Ohio and other Midwestern states. Genealogically, the is common in southwest and , reflecting its as a regional of Coyle among populations. No major celebrities the name, but historical figures include Coil (1852–1911), an in Fayette who later lived in Auglaize and contributed to communities. The occasionally overlaps with artistic pseudonyms , though such uses are not tied to familial bearers.

Organizations and Brands

Capital Coil & Air is a United States-based manufacturer specializing in the production and replacement of commercial and industrial HVAC coils, including booster coils, fan coils, condenser coils, and DX coils, with a focus on custom designs and rapid shipping options. The company, operated by the Jacobs family, traces its roots in the HVAC replacement equipment sector back to 1960, emphasizing OEM replacements and heat exchangers for heating and cooling applications. Headquartered in West Chester, Pennsylvania, it serves a range of sectors by building coils to exact specifications, often providing same-day quotes and stocking common sizes for quick delivery. In the automotive industry, early 20th-century companies played a key role in developing coil spring technologies for vehicle suspensions, transitioning from leaf springs to more compact coil designs that improved ride quality. For instance, Dendoff Springs Ltd., established in 1906 in Canada, began manufacturing coil and other springs for automotive applications, contributing to the sector's growth during the burgeoning automobile era. Similarly, by the mid-20th century, firms like Wolverine Coil Spring, founded in 1946 in Grand Rapids, Michigan, expanded on these foundations to produce precision coil springs, wire forms, and assemblies for automotive components such as rearview mirrors and suspension systems. These historical brands laid the groundwork for modern automotive spring manufacturing, prioritizing high-alloy materials like SAE 5160 steel for durability. Several companies in the oil and gas industry operate under brands incorporating "coil," particularly in coiled tubing services essential for well intervention, drilling, and production optimization. RedHawk Coil Tubing, based in Texas, provides coiled tubing operations, fluid pumping, and mixing services using units capable of handling up to 32,000 feet of 2 5/8-inch coil for efficient wellsite performance. Another example is Coil Tubing Technology Inc. (CTT), which supplies specialized tools and decontamination systems for coiled tubing in oilfield applications, adhering to industry standards since its establishment. These firms highlight the practical branding of "coil" in energy sector technologies, focusing on safety and efficiency in high-pressure environments. Icon of Coil functions as a prominent in the , representing a turned that has released and toured internationally since its in 1997. Founded by as a solo endeavor centered on logo, graphic design, and synth-driven sound, it evolved into a full with releases like Serenity Is the Devil (2000), establishing a recognizable identity in alternative genres. The maintains an active presence through official channels, including remastered anniversary editions and management-handled social platforms, appealing to fans of industrial and futurepop styles. In media and entertainment branding, "Coil" appears as part of Hasbro's G.I. Joe franchise, where The Coil serves as a thematic element in toy lines and comic series produced by partners like Devil's Due Publishing, tying into real-world merchandise such as action figures and exclusive sets released since the early 2000s. This integration extends the brand's reach through licensed products, including figures like the COIL Trooper, which draw from the franchise's narrative while driving consumer engagement in the collectibles market.