## 1 Introduction  
The recent developments of the microsystems have been so promising that nowadays they offer a great potential to many applications which require a high grade of miniaturization. Nevertheless, using microsurgery to heal diseases with a minimal invasive approach is still an ambitious challenge because of severe requirements (accuracy, precision, reliability, reduced consumption, limited costs, small size, high performance repeatability, short response time, efficiency in wet or liquid environments). One way of coping with this challenge consists in modifying the common Micro Electro Mechanical Systems (MEMS) to increase their degrees of freedom (usually unitary) and dexterity, for example, providing them with several revolute pairs. These microsystems need to be tested in a significant environment, starting from room environment (in air), but this is not so obvious as it could appear at first sight. In fact, these systems need to be analyzed by means of SEM, which implies putting the mechanisms within a vacuum chamber, rather than a particular environment. Therefore, significant operational tests must be performed by other means of observations, such as microscopy or interferometric profilometry. However, the latter instruments have less resolution than a SEM and their use can be critical to inspect the smallest parts of a microsystem. This paper shows that microscopy observation can still be very effective in MEMS operational tests under environmental conditions. An effort has been made to assess microscopy observation of MEMS by comparing this means with a higher class, but also a more expensive and difficult-to-use instrument, namely, a profilometer. The statistical treatment of the results of two experimental campaigns (optical microscope and profilometer) shows that the characterization and image acquisition capability of the optical microscope is comparable to that of the profilometer, while the optical microscope maintains a larger degree of freedom in setting the operational parameters. Given the interdisciplinary nature of the present investigation, it is helpful to give a glimpse to the different types of involved competences. It is particularly important to review some previous contributions concerning the operational conditions that would be required to a micro-electro-mechanical system in surgery. A first survey of MEMS for surgical applications [1] showed how MEMS technology may improve the functionality of existing surgical devices and also add new capabilities that give rise to new treatments. For example, MEMS can improve surgical outcomes, with lower risk, by providing the surgeon with real-time feedback on the operation. From the mechanical and operational point of view, microgrippers for different applications have been extensively proposed in literature [2; 3]. There are many other different applications where MEMS can play a significant role. For a representative example, MEMS-Technology based micro-accelerometers [4] are able to measure the heart wall motion of patients who have undergone coronary artery bypass graft surgery (CABG). Furthermore, there are many other applications where MEMS could be conveniently used to improve success in surgery, such as in laparoscopic sleeve gastrectomy (LSG) with curroplasty [5], in surgical treatment of gastrointestinal stromal tumors of the duodenum [6] in colovesical fistula surgery with minimally invasive approach [7], in Endoluminal loco-regional resection by Transanal Endoscopic Microsurgery (TEM) [8; 9; 10], and in Low Rectal Anterior Resection (LAR) [11]. These kinds of applications require very specific actions during the different stages of design, fabrication and packaging, because their correct working is depending on many physical parameters, such as temperature, humidity of the environment, presence of water or other liquids, chemical reactions and pressure.