# A Brief Review on Challenges in Design and Development of Nanorobots for Medical Applications
## 2 Challenges in the Design and Development of Nanorobots  
The architecture of a nanorobot for the purpose of medical applications is presented in this paper [21]. The emergence of biomolecular science and modern manufacturing methods helps advance system miniaturization from micro to nanoelectronics. In recent years, many clinical procedures have been improved with the aid of microdevices in surgery and treatments [6; 7; 8; 9; 17; 18]. This section will discuss the various challenges in the design and development of nanorobots. Nanorobots must be able to perform essential operations such as targeting, energy supply, driving, operating function, and biocompatibility, etc. However, the most significant challenge is nanorobot's work environment and its applications [22]. Depending on the application, various temperature gradients and chemical concentrations in the bloodstream are key parameters in monitoring patients; to incorporate such monitoring practices, the design and development of nanorobots using VHDL (Very High Speed Integrated Circuit Hardware Description Language) has become the popular methodology in the Integrated Circuit (IC) fabrication industry. These upcoming methodologies in manufacturing, and new trends in transducers, computation, and manipulation, have paved the way for the development of nanorobots [23]. Additionally, present-day innovations in nano-electronics and nano-biotechnology could lead to molecular machine manufacturing consisting of sensing, actuation, remote control, uploading, and data transmission; this, in turn, makes the functioning of medical nanorobots possible [6; 7; 8; 9; 17; 18]. Like a conventional robot, nanorobots are developed with a frame and components that can perform sensing and control operations. Today, inorganic material, flagella motors, DNA motors, virus protein linear (VPL) motors, and ATP motors are used to fabricate nanomotors. The main structure of the nanorobot is comprised of the frame component and connections to link each part of the nanorobotic system. These components can be constructed by using inorganic or organic materials, such as DNA and protein. As the connection components are used to link various parts of the robot, the driving component provides the force required to carry out a specific task [22]. Figure 1 depicts basic architecture of a nanorobotic system. A comparison between the architecture of macro robots and nanorobots is provided in Table 1.  
The general challenges faced in the development of nanorobots, regardless of their applications, involve: \begin{table}
\begin{tabular}{c c c} \hline \hline
**Architecture** & **Macro Robots** & **Nano Machines** \\ \hline Sensors & Temperature sensors, Light sensors, Force sensors & CMOS sensors, Nanotubes, Nanowires, Biosensors \\ \hline Actuators & Pneumatic motors, Hydraulic and Electric motors & Flagella motors, DNA and RNA actuators, Protein-based motors (ATP), Liquid-crystal Elastomers (LCE’s) \\ \hline Navigation components & Ball bearings, Belt drives, Gears & \(\beta\) Sheets, sperm-like motors \\ \hline Joints and Links & Prismatic, Spherical, Revolute, Cylindrical & Synthetic joints, Molecular Bonds, DNA hinges, and Nanotubes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison between the architecture of macro robots and nanorobots. Figure 1: Basic architecture of a nanorobotic system. Positional nano assembly that is inefficient in regards to building nanodevices, and this method does not incorporate nanoelectronics,
* DNA approach that cannot be employed to develop complex devices, and
* Bacteria-based nanorobots, incorporating bacteria in the building of nanorobots, present a serious challenge, as bacteria is a living organism and therefore inappropriate due to safety reasons. Performance-wise, nanorobots depend on Brownian motion and electrical noise [17; 18; 21]. It is very well-known that at the nanoscale, the traditional robotics paradigm sensor-actuator-control must be changed due to dimensional constraints. It means all these issues (sensors, actuators etc.)