Piezoresistive sensors for force mapping of hip-prostheses

The success of artificial prosthetic replacements depends on the fixation of the artificial prosthetic component after being implanted in the thighbone. The materials for fixation are subject to mechanical stresses, which originate permanent deformations, incipient cracks and even fatigue fractures. This work shows the possibility of monitoring the mechanical stress over time in prosthesis. In this way, highly sensitive silicon thin-film piezoresistive sensors were developed attached to prosthesis and their results compared with commercial strain gauge sensors. Mechanical stress-strain experiments were performed in compressive mode, during 10,000 cycles. Experimental data was acquired at mechanical vibration frequencies of 0.5 Hz, 1 Hz and 5 Hz, and sent to a computer by means of a wireless link. The results show that there is a decrease in sensitivity of the thin-film silicon piezoresistive sensors when they are attached to the prosthesis, but this decrease does not compromise its monitoring performance. The sensitivity, compared to that of commercial strain gauges, is much larger due to their higher gauge factors (-23.5), when compared to the GFs of commercial sensors (2).

Auschwitz-Pilecki-Huber-Rosa Branca-Ratzinger-Wojtyla!

Estima-se que em Auschwitz tenham morrido, de modo directo, cerca de 1,5 milhões de pessoas. 90% eram judeus. 150 mil polacos, 23 mil ciganos, 15 mil prisioneiros soviéticos, milhares de pessoas de diferentes nacionalidades incluindo, p.e., homossexuais e deficientes físicos e mentais. E ainda cerca de 400 testemunhas de jeová. § It is estimated that at Auschwitz died, directly, about 1.5 million people. 90% were Jews. 150,000 Poles, 23,000 gypsies, 15,000 Soviet prisoners, thousands of people of different nationalities including, eg, homosexuals and physically and mentally disabled. And still about 400 Jehovah's Witnesses.