The phrase "a specially designed apparatus" is correct and usable in written English.
You can use it when referring to a device or tool that has been specifically created for a particular purpose or function.
Example: "The researchers utilized a specially designed apparatus to conduct their experiments more efficiently."
Alternatives: "a custom-built device" or "a tailored instrument".
All applications were performed in a specially designed apparatus.
Static and kinetic friction were measured on a specially designed apparatus.
This study uses a specially designed apparatus and electrical circuit to create the contact arc in a hydrogen air mixture.
Often commercial vehicles, such as trolleys, automobiles, or airplanes, are used to transport the camera; the relatively jerky ride they supply simulates real movement more accurately than does the steady motion provided by a specially designed apparatus.
The arch wires (0.019 × 0.025 inch) were drawn through 0.022-in 0.022-ininleslotteel bracketstainlessiamond, Ormco) fixed on acrylic cylindersteelnted on a specially designed apparatus.
The experimental hydrate plugs are dissociated by the method of symmetric depressurisation, both in a specially designed apparatus and a classical batch reactor.
Liquid and gas permeability measurements for tight gas-sand and shales were done using a pressure transmission technique in specially designed apparatus in which confining pressure, pore pressure, and temperature are independently controlled.
A solution of ethylene vinyl acetate (EVA) copolymer in toluene was used as the adhesive for optical fibers and applied using specially designed apparatus.
The equilibration isopiestic experiments with our specially designed apparatus show that the whole equilibration process is essentially determined by the change processes of the reference standard solutions, and the whole equilibration process can be described approximately by the equation mentioned above.
During the test sequence, the glass samples are mounted in a specially designed calorimeter apparatus.
A specially designed experimental apparatus was built to undertake the tests.
