Adult sex toys are in the midst of a design revolution, says Rita Catinella Orrell, who has written a book on the subject called Objects of Desire.
Orrell, a design journalist based in New Jersey, says that sex toys have become more artistic and sophisticated in recent years due to changing tastes and technological advancements.
"With sales of sexual wellness products projected to grow to $32 billion by 2019, sex toys are an incredible opportunity for new designers," she told Dezeen.
Cheap novelty items once relegated to seedy shops are now "greatly outnumbered by sleek designs made from proven or still-emerging technologies", she added.
Her book, Objects of Desire, is released this month and features over 100 products made for erotic pleasure, ranging from high-tech vibrators and silicone erection rings to whips made of wood and leather.
Orrell came up with the idea for the book a few years ago, when she began to notice that sex toys were winning major industrial design awards.
"One of these award-winning designs was by Yves Béhar," she said, referring to the Swiss designer's collection of vibrators for Jimmyjane.
"I realised that to a designer, this product type was just another challenge in the studio, and I was intrigued by what else was out there."
Through her research, the author discovered several major trends in sex toy design, including wireless charging, 3D printing and toys that come with apps and remote controls.
"Some allow users to interact with each other from anywhere in the world via online interfaces," she said.
Easy-to-clean devices also are popular, with some featuring silicone surfaces that are completely seamless.
"The trend towards using silicone isn't new, but it was an important material advancement about 15 years ago that helped the products transform from disposable novelties to pieces intended to be enjoyed for many years," she told Dezeen.
While pink and black remain the most popular colours, "unisex" hues – such as green and white – are becoming more prevalent, she said.
The author encountered many surprises while doing research for her book. "I didn't realise how popular animal-tail butt plugs are. That one was a shock," she said.
She also was amazed to discover how quickly the sex toy industry adopts new technologies.
"I am still impressed by the artificially intelligent vibrator called HUM that actually allows the vibrator to analyse the feedback response system of the human body, sensing your climax and responding in sync to draw out the experience," she said.
"I didn't realise how incredibly smart these toys could be."
Other standout products, says Orrell, include Pulse II, a "guybrator" that is targeted toward users with mobility issues or erectile dysfunction. Created by Hot Octopuss, the oscillating device wraps the tip of a penis. A man does not need an erection to use it.
The author also was impressed with the Semenette, a dildo with a pump that can be filled with liquid and can mimic the act of ejaculation. The device, from Fun Factory, was recently renamed the Pop Dildo.
Orrell worked for more than a decade as the products editor at Architectural Record magazine and now runs the blog designythings.
Her 270-page book includes colour images, product descriptions and interviews with industry leaders, from a data analyst to a mummy blogger who is a dominatrix.
The author also interviewed Karim Rashid, the industrial designer who created a dildo in 2012 called Mr. Pink. Rashid also designed a sex shop in Munich.
"I hope the book will appeal to both fans of good design, as well as 'lovers' of good design interested in more than just reading about these products," she said.
Objects of Desire was designed by Jason Scuderi and includes a foreword by Sarah Forbes, a curator from New York City's Museum of Sex. Sexologist Carol Queen wrote an introduction for the book about the history and evolution of sex toys.
Recent products designed for erotic pleasure include this bright pink chair that can be mounted like a vaulting horse and this glass vibrator that is powered by clockwork.