Accurate positioning of the needle tip during insertion is essential to ensure a maximum effect of the treatment. Target error is a problem and a lot research fields aim to improve needle insertions. The possibility to measure cutting force and stiffness force separately from friction forces supports the development of new types of needles, needle insertion simulators and needle insertion robots for use in a clinical environment. The goal of this work is to create a needle that can measure these forces. The design is used in an insertion experiment, to determine if this force information can be used to determine tissue properties and differentiate between tissue layers. A new trocar needle design is presented for measuring forces in the tip of the cutting stylet, only measuring the cutting forces and stiffness forces and excluding the friction forces on the shaft. Through the centre of the stylet of a 20 cm 18 G trocar needle runs an optic fibre with a fibre Bragg grating close to the tip, that will function as an optical strain sensor. The interrogator measures the Bragg wavelength shift caused by a change in strain. The grating is embedded in a PVC jacket to increase the strain in the grating. Calibration was performed in a universal test machine to determine the force - wavelength relationship in a range of 0 - 10 N at different constant temperatures. The calibrated prototype was used in insertion experiments in a phantom model and in an ex vivo tissue model. The total axial force is compared to the prototype output. The calibration revealed a linear force - wavelength relationship where the slope coefficient increases with increasing temperature. The calibration showed an average error of 0.1069 N. In the insertion experiment the output of the prototype has a good correlation with the total axial force. Puncture events are clearly identified in both samples. In the phantom tissue it is seen that the different layers can be differentiated by the gradual change in the output profile. The force from the prototype was overestimated, because insertion experiments were performed outside the calibrated temperature range. To conclude force measurement at the tip of needles is feasible, but has to be further investigated. As a first step this design can be improved by the addition of a method for temperature compensation and the improvement of the measurement accuracy.