I suppose I could use a well-characterized spring driven by a cable on a stepper, which then would define the travel, and the strain gauge would define the pressure at that travel. Unfortunately, I need to measure at points about 50 mm apart, over a span of, perhaps, as much as 25 cm. Now it might be possible to get there with a few of these, but that would, I guess, require several passes along that 25 cm target. With a human body, the measurement doesn't need to be terribly precise where soft tissue is present, but where it is just bone under a thin skin, it's quite critical.

Does this appear to you to be something "doable" within the space constraint? Don't forget, it's a human body that's being measured, and we don't want to make holes or tears in the skin.

I'm thinking of a 25 cm steel bar with holes for the probes, and a fixture on which it can be rotated full circle, while holding the bar with the probes quite vertical, or, more specifically, in a precise relationship with the vertical while it is rotated about the member under study. The target is an amputation stump, which has to be fitted quite precisely about the hard regions, but which can be somewhat more "sloppy" in its fit about the soft tissue, when applying a prosthesis.

What's presently done is quite effective for relatively simply shaped stumps, but when there are bony protuberances, or other irregularities, it gets quite tricky, as, the way I've seen it done involves taking a negative cast, which preserves no information about the location of hard surface under a layer of skin and the location of relatively soft tissue. Subsequently, a positive cast is made, which then can introduce error, a socket is made from that, after considerable "modification" based on "educated guesses" about the character of the tissue in various places. This generally produces "adequate" results, but often breaks down.

I'm just curious as to whether it might be possible to "automate out" some of the guesswork.

I think this notion of yours is a good one and, combining deflection that's defined by, say, a stepper, with pressure feedback, from a strain gauge, might offer a good way to get a look at the problem. Unfortunately, the equipment then would be quite massive and prohibitive in its cost.

I know ... I know ... medically-related stuff always is ridiculously costly.

Thanks for the suggestion.

RE