Strained graphene structures: from valleytronics to pressure sensing

Due to its strong bonds graphene can stretch up to 25% of its original size without breaking. Furthermore, mechanical deformations lead to the generation of pseudo-magnetic fields (PMF) that can exceed 300 T. The generated PMF has opposite direction for electrons originating from different valleys. We show that valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by a Gaussian-like deformation allows electrons from only one valley to transmit and a current of electrons from a single valley is generated at the opposite side of the locally strained region. Furthermore, applying a pressure difference between the two sides of a graphene membrane causes it to bend/bulge resulting in a resistance change. We find that the resistance changes linearly with pressure for bubbles of small radius while the response becomes non-linear for bubbles that stretch almost to the edges of the sample. This is explained as due to the strong interference of propagating electronic modes inside the bubble. Our calculations show that high gauge factors can be obtained in this way which makes graphene a good candidate for pressure sensing.Comment: to appear in proceedings of the NATO Advanced Research Worksho

Primary adenocarcinoma of the fallopian tube mimicking pelvic inflammatory disease.

Primary fallopian tube carcinomas are rare and are difficult to diagnose preoperatively. We describe a fallopian tube carcinoma in a 50-year-old lady who presented with symptoms of pelvic inflammatory disease. Ultrasound examination showed bilateral hydrosalphinx. However, CT scan showed features suggestive of a malignant ovarian tumour. At surgery, a markedly dilated left fallopian tube was found and histopathological examination confirmed the presence of a primary serous adenocarcinoma. The uterus and both ovaries were free of tumour. This report highlights that carcinoma of the fallopian tube should be considered as a differential diagnosis in females who present with lower abdominal pain