This paper presents and discusses the liquid density sensing potential of a delay line Lamb-wave sensor configuration, where Lamb wave is excited only by interdigital transducer (IDT), without membrane when fabricated. An optimized cut orientation and the normalized thickness of substrate by using genetic algorithm is presented to improve the sensitivity of the sensor and to get low noise. Experimental measurements performed on Lamb-wave device fabricated from Y-Z LiNbO3 in a delay line configuration are found to be in agreement with theoretical calculations.