The phrase "an indispensable device" is correct and usable in written English.
It can be used to describe a device that is absolutely necessary or essential in a particular context or situation.
Example: "In today's digital age, a smartphone has become an indispensable device for communication and information access."
Alternatives: "a crucial tool" or "an essential gadget".
The mobile phone has become an indispensable device in everyday life.
Polarizer is an indispensable device in a wide range of optical systems, including flat panel displays, microdisplays, and optical networking.
It is an indispensable device to study the protective efficacy of vaccine candidates against Mycobacterium tuberculosis infection.
According to Line, Idezawa's accomplishments during his 12 months as COO include Line's new "LIFE platform strategy," which wants to turn the app into "an integral part of everyday life in an era where smartphones have evolved into an indispensable device for people all over the world".
I'm a voracious Apple Watch user, and, after over a year of allowing it to rub up against the real world with all of its indignities, I think that a healthy dose of simplification and physicality could help it move from something for gadget lovers and fiddlers to a truly indispensable device that acts as an interface between the physical and digital worlds.
For Nokia, the cellphone's growing role as the indispensable device in a wireless, Web-connected world ought to be a boon.
The failure of technology has been an indispensable plot device ever since Gulliver's shipwrecks.
The electric powered wheelchair (EPW) is an indispensable assistive device that increases participation among individuals with disabilities.
When I read the recent news that Google has unveiled a voice-activated "Conversation Mode" for its Translate app (for Android), I immediately thought of Star Trek's "universal translator" — that uniquely improbable and indispensable device that allows creatures from different planets and galaxies to communicate.
They have become indispensable devices for millions of Americans and have spawned the "app economy" — there are over eighty-five thousand applications for these devices today.
For solid-state quantum information processing, microcavities and nanocavities containing semiconductor quantum dots (QDs) have been demonstrated to be effective as indispensable devices such as efficient [3 5] and indistinguishable single-photon sources (SPSs) [6, 7] and coherent quantum-control devices [8, 9].
