El Cajon-based Sigma Systems, a manufacturer of environmental testing chambers, has been acquired by New Jersey-based inTEST Corporation, inTEST said Tuesday. Financial terms of the acquisition were not disclosed. inTEST said that Sigma Systems will become part of the firm's Temperature Management product segment. Sigma Systems develops environmental chambers and thermal testing products which are used in the semiconductor, automotive, medical/pharmaceutical, electronics, and aerospace industry. InTEST said that Sigma Systems was founded in 1956.