The Laplacian of the body surface potentials (Laplacian ECG--LECG) is a new approach to resolve spatially distributed bioelectric sources. LECG is a weak signal so an LECG sensor needs a good signal-to-noise ratio (SNR) and high common mode rejection ratio (CMRR). In this paper, we discuss a LECG sensor, which integrated tripolar concentric ring electrodes and signal conditioning circuit on a printed circuit board. The experimental results are in agreement with the theoretical calculations suggesting the feasibility of measuring the surface Laplacian. This lays the foundation for using such a device to assist in heart disease diagnoses.