Biology and Engineering: Arthropod Force Detectors

Among the arthropods like insects and spiders one finds a staggering variety of exquisite micro-sensors. The present project is an initiative to bring together biologists and engineers in an effort to better understand a highly refined force and strain sensing system embedded in the cuticular exoskeleton of spiders and to model and indeed fabricate novel artificial force/strain sensors with medical and industrial applications based on biological principles. The specific force detectors addressed by the project are the spider slit sensilla. These form a system of about 3,500 tiny sensory holes (width ca. 1 m, length from 8 to 200 m) in the exoskeleton. The sensory neurons attached to them respond to minute strains down to a few e (ppm) which are set up in the exoskeleton surrounding the slits mainly by muscular activity, blood pressure, and substrate vibration. A particularly intriguing feature of the slit sensilla is that they form a diversity of arrays with up to 30 slits arranged roughly in parallel and referred to as the compound or Iyriform organs. Previous studies indicated a fascinating complexity here, both in regard to the mechanical properties of the stimulus transforming cuticular structures and the physiological properties of the nervous responses. The fresh approach making use of highly advanced computational modeling technologies now available will allow a new level of analysis and quantification. The project will focus on processes of stimulus transformation and on the sensor`s output signals (action potentials). lt promises new insights into the ,,tricks" hidden in the rnechanical design of the spider cuticular force sensors. We assume these ,,tricks" to be tailor-made to the specific measuring task of the various slits and slit arrays at the different locations of the exoskeleton and to correspond to properties such as absolute, directional, and differential sensitivity, frequency tuning and range fractionation. Thus the project will combine experimental research and computational modeling with sensory biology. The biologists will concentrate on the fine structural analysis of the sensor arrays and on the electrophysiological recording of the nervous responses (impulses) of the sensory cells to biologically relevant stimuli. The engineers engaged in the project are specialists in numerical methods and will apply Finite Element methods and fracture mechanics to simulate the complex deformation behavior of single slits and in particular of slit arrays. Likewise experts in micro-technology will work on the design of a novel biology-inspired technical force sensor and develop ways of its fabrication. Given the refinement of biological sensors and considering the increasing importance microand nanosensors have gained for industrial and medical applications in recent years the flow of knowledge and ideas from biology to engineering is as obvious a source of innovation as is the engineering approach for biology.

Among the arthropods like insects and spiders one finds a staggering variety of exquisite micro-sensors. The present project is an initiative to bring together biologists and engineers in an effort to better understand a highly refined force and strain sensing system embedded in the cuticular exoskeleton of spiders and to model and indeed fabricate novel artificial force/strain sensors with medical and industrial applications based on biological principles. The specific force detectors addressed by the project are the spider slit sensilla. These form a system of about 3,500 tiny sensory holes (width ca. 1 m, length from 8 to 200 m) in the exoskeleton. The sensory neurons attached to them respond to minute strains down to a few e (ppm) which are set up in the exoskeleton surrounding the slits mainly by muscular activity, blood pressure, and substrate vibration. A particularly intriguing feature of the slit sensilla is that they form a diversity of arrays with up to 30 slits arranged roughly in parallel and referred to as the compound or Iyriform organs. Previous studies indicated a fascinating complexity here, both in regard to the mechanical properties of the stimulus transforming cuticular structures and the physiological properties of the nervous responses. The fresh approach making use of highly advanced computational modeling technologies now available will allow a new level of analysis and quantification. The project will focus on processes of stimulus transformation and on the sensor`s output signals (action potentials). lt promises new insights into the ,,tricks" hidden in the rnechanical design of the spider cuticular force sensors. We assume these ,,tricks" to be tailor-made to the specific measuring task of the various slits and slit arrays at the different locations of the exoskeleton and to correspond to properties such as absolute, directional, and differential sensitivity, frequency tuning and range fractionation. Thus the project will combine experimental research and computational modeling with sensory biology. The biologists will concentrate on the fine structural analysis of the sensor arrays and on the electrophysiological recording of the nervous responses (impulses) of the sensory cells to biologically relevant stimuli. The engineers engaged in the project are specialists in numerical methods and will apply Finite Element methods and fracture mechanics to simulate the complex deformation behavior of single slits and in particular of slit arrays. Likewise experts in micro-technology will work on the design of a novel biology-inspired technical force sensor and develop ways of its fabrication. Given the refinement of biological sensors and considering the increasing importance microand nanosensors have gained for industrial and medical applications in recent years the flow of knowledge and ideas from biology to engineering is as obvious a source of innovation as is the engineering approach for biology.