Try googling x ray art. There’s some neat stuff there that fits, and it’s interesting enough to be a conversation starter rather than a conversation killer for dates who see it. 
Well maybe some of Richard Powers’ stuffwill fill the bill … it can be cold, sterile and vaguely menacing one moment, and inspiring the next. Sometimes, both at the same time. The best science fiction art EVAH!
Nooo. Don’t give up now :D. We have more suggestions: Kvium, for instance, might fit the bill (though his work will probably ward off any chance of romance in your flat).
Well, I was going to suggest H.R. Giger, too, but I’m not sure he qualifies as “sterile”…his stuff always looked a bit squishy.
Maybe some early computer art? Some of Ken Knowlton’s non-portrait stuff seems to fit the bill.
If you want “sterile” AND “menacing,” maybe some old fascist or communist propaganda posters, if they’re stylized enough, but especially if they’re of a seemingly innocuous subject or motivation until you look a little closer. This one’s always been a favorite of mine, though anything with a smiling art deco guy with dead eyes should do the trick. 
I thought I didn’t really like art…turns out I like it fine if it’s creepy enough. 
At a nearby medical clinic, for Halloween one year they made a “skeleton” on the wall out of old X-rays of different parts of the body, every one with something horrible having happened to it. Broken bones, scissor impalement, growths…it was one huge injury horrorshow that no single human could have borne. It was awesome.
Woah. I’d love to see that.
I saw something similar at the Hunterian Museum (the collection of the Royal Society of Physicians in London, England - highly recommended for those interested in the grotesque). Though a sculpture rather than an xray.
Here, have at it.
That leads to an error. Can you fix the link?
Curious, me?
A photographer friend of mine is one of the many people specializing in photographing empty, derelict houses and the stuff people just left there. her pictures are delicate, beautiful, strong, and incredibly lonely, cold and sad.
Several of her pictures have been made into dustjackets.
Here are some examples.
A swan landing on water
Cross on windowsill
A bed
Empty interior
She even managed to make a picture of me, when I was eight months pregnant, into something saddish.
You can just google “articulomortis”. I was just browsing the site a few minutes ago and now my book mark is giving me the same error page; I think Tumbler is having a problem at the moment; when they sort it out my orig link should work.
Enough images there to keep you occupied for days.. some images make you re-think about your mortality in much matter-of-fact reality. It’s one of those I can’t believe I’m looking at these pictures but I can’t stop kind. Note: hover over the image to make them clear.
Hey, great stuff! 
In return, here’s some images from the Hunterian Collection (warning, grotesque):
http://www.toimg.net/managed/images/10170269/w482/h298/image.jpg
http://www.immortalitymedicine.tv/wp-content/plugins/wp-o-matic/cache/e02dc_anatomicaltheatre73.jpg
Thanks, brittekland!
Cold and sterile, but utterly beautiful: snow flakes. I ordered a poster from that site and enjoyed it very much untill it got damaged in a house move.
Along the lines of the Hunterian Collection, there’s a book called Dissection: Photographs of a rite of passage in American medicine 1880-1930, which features vintage (late 19th, early 20th century) photos of medical school students dissecting human cadavers…and, aside from “class photos,” sometimes posing the (often skinned or already very dissected) bodies in funny ways, like propping them up around a table to make it look like they’re dissecting a student, or playing cards, etc.
Samples and links to samples here! (Obvious warning: Contains creepy photos of graphically mangled corpses in amusingly creepy poses)
Probably not very sterile, but the guy who does Romantically Apocalyptic has a deviant art store with prints of various prices: http://alexiuss.deviantart.com/prints/
When I think of sterile and menacing, all I think of is architecture. Anything with a living element to it rules out sterile for me.
So I think of things like this:
Wow, I like that! I don’t see it as sad, unless you go into it thinking that. It’s almost a paean to the long-term endurance a pregnancy wrests of you whether you think you are up to it or not. 
Speaking of menacing architecture, how about this line drawing? The oppressive sun, the coil of wires…