 Biomedical engineer

A biomedical engineer develops, investigates or evaluates systems at the intersection of engineering, biology and medicine. Work can include instrument design, biomechanics, biomaterials, data analysis and technical support for medical equipment. The role includes constructing models and experiments, not only assembling a finished device.^[ref]

An original load cell example makes the measurement work concrete. Suppose reference loads $F=2\mathrm{N}$ and $6\mathrm{N}$ produce outputs $V=0.30\mathrm{V}$ and $0.70\mathrm{V}$. Fitting the stipulated linear measurement model $V=kF+b$ givesA later output of $0.50\mathrm{V}$ then corresponds to $4\mathrm{N}$. Ignoring the offset would instead report $5\mathrm{N}$. With the calibration coefficients held fixed, an output uncertainty of $0.01\mathrm{V}$ contributes $0.10\mathrm{N}$ to force uncertainty; uncertainty in the reference loads and fitted coefficients adds further terms.

The engineer must also determine whether that model remains useful. A third reference load tests interpolation; repeated loading and unloading can reveal hysteresis; a temperature change can expose drift. Mounting the sensor on a biological specimen can alter the load path compared with the calibration fixture. Thus a satisfactory calibration curve is one part of demonstrating fitness for the intended measurement. Collaborating with users and reporting the conditions and limitations connects engineering performance to the biological question.