## 5 Insights for Development of Proprioceptive Soft MIS Manipulators  
The studies on the development and integration of sensing conducted during the STIFF-FLOP project have highlighted the complex challenges involved in developing soft surgical manipulators. The robotic requirements bring to fore the technological challenges. The key technological challenges relating to actuation and sensing can be summarized into (a) enhancing dexterity, (b) achieving proprioception and exteroception, and (c) data fusion, information extraction for visualization and control. In the following synopsis, we  
Figure 12: (**A**) Abraded fibre-based bending sensor shows optical loss through the cladding and decrease in light intensity measured by the receiver corresponds to the bending curvature; (**B**) Schematic of a pneumatically controlled soft finger sensorized by the fibre-based sensor; (**C**) (top) the bending shape of the finger under different input pressures and (bottom) the sensor response during the bending process [36]. elaborate on the research paths that lie ahead in terms of solving both the actuation and sensing challenges:  
1. _Miniature and addressable actuation:_ Challenges still remain in terms of achieving dextrous soft manipulators that meet the requirements of minimally invasive surgical applications. A major technical challenge with respect to actuation can be summarised as the development of miniature soft actuators capable of achieving sufficient forces for procedures such as tissue biopsy powered by a compact and addressable fluidic system. Modular soft actuator systems that share a single fluidic source have the capability to reduce the size of fluidic channels connecting the power source to the actuators distant from the base of the manipulator [44]. Application specific solutions involving multi-stage deployable structures for anchoring may help to solve the force generation challenges in miniature surgical manipulators;
2. _Novel technologies for multi-modal and miniaturised sensing:_ Analogous to addressable actuation offering high dexterity, achieving a high degree of freedom sensing within size constraints is also challenging. Multi-modal sensing from a single sensor system and distinguishing between multiple modes of sensor feedback will help to reduce the number of sensors needed, thereby reducing space requirements [6]. Novel technologies such as optical waveguides with chromatic patterns that discern the location of stimuli are crucial for sensorizing dexterous soft manipulators. Akin to capacitive and resistive tomography-based methods, researchers are also pursuing techniques involving multiple light sources and detectors to develop sensor skins [45; 46];
3. _Co-design of actuation and sensing structures:_ Designing the sensor layout and structure with intended function in mind is important to address the joint challenges of dexterity and proprioception. Effective use of pressure-insensitive sensors, in conjunction with sensors that are responsive to interaction forces, can help to distinguish between sensor readings due to pose change and external stimuli. Task-based selection of optimal sensor layout will be useful in reducing the number of sensors required [47]. Artificial Intelligence based approaches to learning the robot's task with sparse sensor placement are also improving the effectiveness of available sensor data [26]. There is also scope for the development of algorithms that take into account the multi-stimuli responsiveness of soft lightguide-based sensors and achieve sensor selection and placement to enable proprioception in the event of interactions with the environment. Algorithms that can automatically co-design the actuator layout along with the sensor layout based on the specific surgical task requirements will be a significant step towards soft manipulators for MIS;
4. _Machine learning and AI for sensor-data processing:_ To tackle strict processing challenges, we need to adopt efficient data processing approaches.