The phrase "an ever more sensitive" is correct and usable in written English.
It can be used to describe something that is increasingly sensitive over time, often in contexts related to emotions, reactions, or perceptions.
Example: "In today's society, we are witnessing an ever more sensitive approach to discussions about mental health."
Alternatives: "an increasingly sensitive" or "a progressively sensitive".
In the meantime, they used the prototype at Caltech and a facility in Germany to develop ever more sensitive mirror, laser, and seismic-isolation technology.
In forensic science it is very often necessary to "first find your sample," so searching for suitable samples is an integral part of the job, and with the introduction of ever more sensitive analytical techniques such samples can be smaller and smaller.
Most physicists and cosmologists saw the developments in a positive light, since expected improvements in both detectors should allow ever more sensitive searches for the mysterious particles, and -- perhaps -- solve a problem that astronomers have grappled with since gathering the first indirect evidence for the existence of dark matter nearly 70 years ago.
For several years, the armed forces have been intensifying the search for ever more sensitive devices.
Our ever more sensitive technologies turn up more and more abnormalities — cancers, clogged arteries, damaged-looking knees and backs — that aren't actually causing problems and never will.
We are what we drink (and eat and inhale), according to ever more sensitive tests probing the trace constituents of the internal human environment.
As divisions of large corporations with broad-ranging interests, Hollywood studios have become ever more sensitive about movies with controversial content, whether sex, religion or politics.
Shuttle astronauts corrected the vision defect, regularly replaced failing gyroscopes and installed ever more sensitive instruments, allowing Hubble to provide brilliantly sharp images.
Since we calculate the length of survival from the time of diagnosis, ever more sensitive screening starts the clock ticking sooner.
And then, of course, there is the call of history, to which this prime minister's ears appear to grow ever more sensitive.
