Ultrasonically actuated silicon-microprobe-based testicular tubule metrology

We report on a microfabricated silicon microprobe integrated with an ultrasonic actuator and polysilicon strain gauges for Microdissection Testicular Sperm Extraction (TESE) surgery. Multiple microprobe insertion experiments were performed on rat testis tissue and, by monitoring the tubule puncture artifacts in the force signal sensed by the microprobe, we were able to estimate the average diameter of the sperm-carrying tubules in the sample. We have demonstrated the ability to sense the existence of larger tubules embedded in a mass of thinner tubules, by means of an Area-Ratio based metric using an analytically calculated expression for the distribution of sizes measured by the microprobe. This information is important in microdissection TESE to distinguish tubules with and without fertile sperm, potentially eliminating the large incision currently required for optical spermatazoa localization.