'indispensable device' is correct and usable in written English.
You can use it to describe something that is essential or necessary for accomplishing a certain task. For example, "The smartphone has quickly become an indispensable device for many people around the world."
The mobile phone has become an indispensable device in everyday life.
For Nokia, the cellphone's growing role as the indispensable device in a wireless, Web-connected world ought to be a boon.
It is an indispensable device to study the protective efficacy of vaccine candidates against Mycobacterium tuberculosis infection.
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.
Polarizer is an indispensable device in a wide range of optical systems, including flat panel displays, microdisplays, and optical networking.
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".
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.
Wherever the polarization properties of a light beam are of concern, polarizers and polarizing beamsplitters (PBS) are indispensable devices in linear-, nonlineand and quantum-optical schemes.
It is the carriers who turn out shiny baubles into indispensable devices that keep us plugged into the web.
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].
Knowledge of both carrier and phonon dynamical properties is indispensable for device engineers to design better and faster devices.
