From a comparison between curves (i) of figures 1a and and1b1b it is also evident that the immobilization procedure doesn’t significantly alter the UV fluorescence spectra according to ref. 21
In recent years,various optical 3D-sensors have become available and are nowadays used in many different fields of work, e.g., reverse engineering or quality management in industrial tasks, cultural heritage, medicine and also criminal investigations [1]. Several different sensor technologies can be used for 3D digitizing, like terrestrial laser scanners (TLS), triangulation-based range sensors or photogrammetric approaches, like stereo cameras or bundle adjustment of multiple images [1�C7]. All of these sensors have their own limitations regarding flexibility, measuring volume, spatial resolution and accuracy.

For most applications, it would be sufficient to capture wide areas with an adequate spatial resolution and selected items, like, e.g., statues [5] or evidence objects [8] with a lot more details. Such a demand requires the fusion of different sensors, because a single sensor type is commonly not able to fulfill both requirements. Using low-cost sensors exacerbates this demand. These sensors have more strict limitations regarding measuring volume and resolution.The advantages and potentials of the combined usage of multiple sensors were presented early on [9] and are used nowadays in a wide range of applications, e.g., the navigation of an unmanned aerial vehicle (UAV) [10], cultural heritage [2�C5] and criminal investigation [6�C8].

In the field of 3D digitizing, the most frequently used sensor combination consists of a TLS and a digital camera. This combination enables an efficient, flexible and reliable acquisition of large objects, with the advantage of a high spatial resolution and photorealistic representation, and it is mostly used in terms of the documentation of cultural heritage. Many different applications Dacomitinib are presented in the literature, where TLS and photogrammetric measurements are used to build a multi-resolution 3D model of well-known cultural sites, e.g., Villa Giovanelli [4] or Pozzoveggiani Church [5], and much more. All of these approaches use manual or semiautomatic algorithms to align point-clouds of different sensors, which are time-consuming and need trained operators.Similar approaches can also be found in the field of crime scene documentation. An accurate geometrical conservation of crime scenes is of high interest, because the risk of losing evidence by modification by forensic staff, spectators and witnesses is immense. Large scenes have to be acquired quickly and non-invasively, as well as for single evidence objects with high resolution, e.g., for the reconstruction of a ballistic trajectory.

Some applications of autonomous sensors can be founded in remote monitoring apparatus for the measurement and recording of physiological parameters [8-11]. Autonomous sensors are applied on live animals for analysis of brain stimulants to analyze neurochemical data for research purposes. These systems are small and light enough to record biopotentials from awake birds and insects. This technique allows, for example, real-time reading of glucose levels in diabetic patients, critical care and brain injuries. In orthopedic science autonomous sensors are used for accurate measurements of knee forces in total knee arthroplasty [1]. These forces produce wear in polyethylene, stress distribution in the implant and the implant�Cbone interface, and stress transfer to the underlying bone.

Autonomous sensors are adopted in many other fields: in the literature applications in harsh environments are described, such as under high temperatures, cold, humidity or corrosive conditions [12-17]; applications in which long distances are to be bridged or a big number of distributed components is necessary, such as smart homes, environmental applications [18] or mobile applications for the monitoring of environmental conditions [19]. Common examples of applications are the structural health monitoring of bridges or buildings [20] and the monitoring of climate conditions or pollution [21]. In environmental monitoring flow and temperature are important parameters for efficient control of domestic or industrial plants [22].

In these cases, temperature values along the sections of a heating or cooling plant are important indicators to control the energy efficiency in the regulation of thermal comfort [23-24].Usually an autonomous sensor requires a power source: several examples reported in literature are equipped with batteries, but other power sources are emerging such as: harvesting modules and inductive links. Since the voltage and current levels of the electronic circuits do not currently meet the possibility offered by power harvesting system or sometimes even by batteries, management of the power supply is required; this block commonly consists of a dedicated DC-DC converter and power supervision circuits. Several sensors are powered by rechargeable batteries [18-19]. However, batteries frequently dominate the size and weight of the device.

Batteries introduce unwanted maintenance burdens of replacement and, they often cannot be easily replaced since the autonomous sensor is placed in a protected environment. Moreover, GSK-3 the disposal of the increasing number of batteries is creating an important environmental impact as they contain toxic chemicals.Since autonomous sensors are wireless devices, they encounter the typical problems of a wireless network. If the distance between the wireless device and the data collection system is short, a point to point communication can be implemented.