Cell microinjection plays an important role in genetics, transgenics, and other biomedical fields. As compared with manual cell microinjection and position-based robotic cell microinjection, force-assisted robotic cell microinjection can improve the success rate and survival rate of the injected cells. In this paper, a novel force-sensing cell injector is designed with piezoresistive force sensor embedded in soft materials. The soft sensors act as fixed-guided beams, which are introduced to achieve the force measurement with high sensitivity in pure one-degree-of-freedom (1-DOF) direction. The injector is developed by considering the installation and replacement issues of the micropipette as well as the connection convenience between the micropipette and tube of compressed air. A prototype of the cell injector with the force sensor is fabricated. Experimental study is conducted to verify its performance in practice.