high-Tc SQUID, magnetometer, bio-magnetism, multi-channel, rat MCG. Abstract. Three-channel directly-coupled-type high-Tc SQUID magnetometer array, with pick-up coil size of 1.5 mm2 comparable to the lift-off distance of the developed multi-channel SQUID system, was designed. In this design, two slits were introduced in the SQUID ring to improve the inductive coupling between the pick-up coil and the SQUID ring to obtain the field sensitivity of about 700 fT/Hz1/2. With the SQUID array that was mounted on the multi-channel SQUID system, the measurements of magnetocardiogram of rat were demonstrated to evaluate the system performance.