Luigi Pinna | Università degli Studi di Genova (original) (raw)

Papers by Luigi Pinna

Endowing appliances with the capability of sensing and processing touch enables tactile interacti... more Endowing appliances with the capability of sensing and processing touch enables tactile interaction between electronic devices and the environment. E-skin organized as a set of multiple sensing components and integrated with a dedicated embedded electronic system can implement the communication link between e-skin and surroundings. Basing the analysis on a relevant application example (i.e. human prosthetics), the present study describes a system including an electronic skin and a stimulation unit. The overall system was validated and tested in eight healthy subjects, who were asked to recognize the shape, position and direction of a set of dynamic mechanical stimuli presented on the electronic skin. The results demonstrated that tactile information was successfully translated from a mechanical interaction applied on the e-skin into electrotactile patterns, which the subjects could recognize with a good performance. As the obtained results are promising, in this paper the challenging requirements for the integration of e-skin into prosthetic devices were assessed, mainly focusing on computational complexity of the embedded data processing unit.

Integration, Sep 1, 2018

Embedding electronics with tactile sensors may enable electronic skin to be applied in many domai... more Embedding electronics with tactile sensors may enable electronic skin to be applied in many domains such as prosthetics, robotics, industrial automation. The complexity of electronics from size and power consumption point of view represents the main barrier towards achieving goal. This paper provides the experimental characterization of dedicated front-end electronics for piezoelectric tactile sensing arrays. Aiming to decrease the hardware complexity, the designed circuits are based on the DDC112U and an FPGA Xilinx Spartan-6 devices. An experimental setup has been implemented to acquire the signal generated from a tactile sensor. Results validate the functionality of the proposed interface when the measured voltage and charge are analyzed in terms of the input force. Experimental characterization demonstrates the correctness of the results when the signal to noise and distortion (SINAD) ratio, and the effective number of bits (ENOB) have been analyzed.

Development of tactile sensing systems is motivated by the possibility of application in many dom... more Development of tactile sensing systems is motivated by the possibility of application in many domains such as robotics, prosthetics, and industrial automation. This paper provides a functionality assessment of an interface electronic circuit prototype for tactile sensing systems. The circuits are based on the DDC112U and an FPGA Xilinx Spartan-6. An experimental setup is carried out to measure the signals generated from a single tactile sensor. Experimental results validate the correct functionality of the proposed interface when the measured voltage and charge are analyzed in terms of the input force. Moving to the new system may pave the way towards the fully integrated SoC for the e-skin development.

Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb.... more Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb. To foster prosthesis embodiment and functionality, it is necessary to re-establish both volitional control and sensory feedback. Contemporary feedback interfaces presented in research use few sensors and stimulation units to feedback at most two discrete feedback variables (e.g., grasping force and aperture), whereas the human sense of touch relies on a distributed network of mechanoreceptors providing high-fidelity spatial information. To provide this type of feedback in prosthetics, it is necessary to sense tactile information from artificial skin placed on the prosthesis and transmit tactile feedback above the amputation in order to map the interaction between the prosthesis and the environment. This paper will provide a perspective on the use of distributed sensing and electrical stimulation systems for the restoration of the sense of touch in prosthetics.

We present an event-driven tactile sensing element that encodes both the absolute value of the in... more We present an event-driven tactile sensing element that encodes both the absolute value of the input force and its variation over time. It is based on the POSFET device and Leaky-Integrate and Fire neurons, connected by a transconductance amplifier; the proposed circuit exploits the advantages of the POSFET device, such as high integration scale, fast response, wide bandwidth and force sensitivity, as well as the advantages of event-driven encoding, such as low latency, low power dissipation, and high temporal resolution, coupled with redundancy reduction.

IEEE Transactions on Circuits and Systems I-regular Papers, Jun 1, 2017

We present a low-power compact circuit for the event-driven readout of tactile sensors. The taxel... more We present a low-power compact circuit for the event-driven readout of tactile sensors. The taxel is based on the POSFET device, a sensotronic unit where a piezo-electric material is deposited on the gate of a transistor, integrated with a Leaky-Integrate and Fire neuron circuit. This device encodes the applied force with trains of digital pulses, using the asynchronous Address Event Representation protocol. The instantaneous output spiking frequency is directly proportional to the force applied to the taxel. We show a full characterization of the device as well as quantitative measurements from a prototype fabricated on AMS CMOS 350-nm process. The taxel can reliably distinguish applied forces from 0.1 N up to 1.5 N.

Electronic skin can be integrated into a prosthetic device to endow the prosthesis with artificia... more Electronic skin can be integrated into a prosthetic device to endow the prosthesis with artificial cutaneous sensing, thereby partially restoring the sensory information lost due to an amputation. Non-invasive cutaneous electrostimulation transmits the tactile information sensed by the electronic skin on the prosthetic hand to the human brain, through the amputee's afferent nervous system. In this paper, our current benchtop prototype of a distributed sensing-stimulation system is presented, together with the envisaged high-fidelity solution which will be integrated into a real prosthetic hand.

IEEE Sensors Journal, Sep 15, 2017

In this paper, we propose a novel design approach for the interface electronics of piezoelectric ... more In this paper, we propose a novel design approach for the interface electronics of piezoelectric polymer tactile sensing systems. An interface electronics prototype based on commercial off-the-shelf (COTS) components having the same operating principle as the proposed approach has been fabricated. The system has been validated by using an experimental setup where electrical and electromechanical characterization are carried out. The interface electronics measures charge of about 0.15pC for applied forces as low as 12.5mN at the working frequency of 27Hz. The experimental average sensitivity of the system is 0.6pC/kPa in the frequency range from 10Hz to 250Hz. Long term goal is to miniaturize the interface electronics for the development of embedded tactile systems in prosthetic and robotic applications.

2018 IEEE International Symposium on Circuits and Systems (ISCAS), 2018

The lack of tactile sensation in current upper limb prostheses is the key limitation to enable mo... more The lack of tactile sensation in current upper limb prostheses is the key limitation to enable more intuitive use of the prosthesis and restore the functionality of the natural limb. Electronic skin in the form of tactile sensing arrays can be integrated onto the upper limb prosthetic device to record information about touch, given back to the amputee as a sensory feedback. This contribution focusses on the development of tactile sensing arrays based on PVDF-TrFE piezoelectric polymers. Both piezoelectric polymer sensors and metal contacts have been screen-printed on a transparent plastic foil. The geometric layout and size of the 4×4 array is suitable for prosthesis fingertips. Preliminary experimental validation of the skin patches is reported in this paper.

2018 IEEE International Symposium on Circuits and Systems (ISCAS), 2018

Closing the prosthesis control loop by providing tactile sensory feedback to the user is a key po... more Closing the prosthesis control loop by providing tactile sensory feedback to the user is a key point in research on active prosthetics as well as an often cited requirement of the prosthesis users.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

The present research aimed at providing myoelectric prostheses with a comprehensive artificial cu... more The present research aimed at providing myoelectric prostheses with a comprehensive artificial cutaneous sensing to enable bidirectional communication. Preliminary experiments showed that subjects could recognize shape, position and direction of basic and more complex touches with a reasonable success rate. This sensory feedback system appears feasible and intuitive.

2017 New Generation of CAS (NGCAS), 2017

Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb.... more Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb. To foster prosthesis embodiment and functionality, it is necessary to re-establish both volitional control and sensory feedback. Contemporary feedback interfaces presented in research use few sensors and stimulation units to feedback at most two discrete feedback variables (e.g., grasping force and aperture), whereas the human sense of touch relies on a distributed network of mechanoreceptors providing high-fidelity spatial information. To provide this type of feedback in prosthetics, it is necessary to sense tactile information from artificial skin placed on the prosthesis and transmit tactile feedback above the amputation in order to map the interaction between the prosthesis and the environment. This paper will provide a perspective on the use of distributed sensing and electrical stimulation systems for the restoration of the sense of touch in prosthetics.

Organic Electronics, 2016

This paper reports on a highly sensitive tactile sensor based on a floating gate organic transist... more This paper reports on a highly sensitive tactile sensor based on a floating gate organic transistor called Organic Charge Modulated FET coupled with a flexible piezoelectric polymer (namely a film of polyvinylene fluoride, PVDF). The proposed device is able to reliably transduce pressures as low as 300 Pa, thus opening up interesting perspectives for flexible and low-cost tactile sensors for e-skin applications.

2016 12th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME), 2016

Endowing appliances with the capability of sensing and processing touch enables tactile interacti... more Endowing appliances with the capability of sensing and processing touch enables tactile interaction between electronic devices and the environment. E-skin organized as a set of multiple sensing components and integrated with a dedicated embedded electronic system can implement the communication link between e-skin and surroundings. Basing the analysis on a relevant application example (i.e. human prosthetics), the present study describes a system including an electronic skin and a stimulation unit. The overall system was validated and tested in eight healthy subjects, who were asked to recognize the shape, position and direction of a set of dynamic mechanical stimuli presented on the electronic skin. The results demonstrated that tactile information was successfully translated from a mechanical interaction applied on the e-skin into electrotactile patterns, which the subjects could recognize with a good performance. As the obtained results are promising, in this paper the challenging requirements for the integration of e-skin into prosthetic devices were assessed, mainly focusing on computational complexity of the embedded data processing unit.

IEEE Sensors Journal, 2014

This paper presents the advanced version of novel piezoelectric oxide semiconductor field effect ... more This paper presents the advanced version of novel piezoelectric oxide semiconductor field effect transistor (POSFET) devices-based tactile sensing chip. The new version of the tactile sensing chip presented here comprises of a 4 × 4 array of POSFET touch sensing devices and integrated interface electronics (i.e., multiplexers, high compliance current sinks, and voltage output buffers). The chip also includes four temperature diodes for the measurement of contact temperature. Various components on the chip have been characterized systematically and the overall operation of the tactile sensing system has been evaluated. With new design, the POSFET devices have improved performance [i.e., linear response in the dynamic contact forces range of 0.01-3 N and sensitivity (without amplification) of 102.4 mV/N], which is more than twice the performance of their previous implementations. The integrated interface electronics result in reduced interconnections which otherwise would be needed to connect the POSFET array with off-chip interface electronic circuitry. This paper paves the way for CMOS implementation of full on-chip tactile sensing systems based on POSFETs.

IEEE Sensors Journal, 2013

The paper focuses on the manufacturing technology of modular components for large-area tactile se... more The paper focuses on the manufacturing technology of modular components for large-area tactile sensors, which are made of arrays of polyvinylidene fluoride (PVDF) piezoelectric polymer taxels integrated on flexible PCBs. PVDF transducers were chosen for the high electromechanical transduction frequency bandwidth (up to 1 kHz for the given application). Patterned electrodes were inkjet printed on the PVDF film. Experimental tests on skin module prototypes demonstrate the feasibility of the proposed approach and reveal the potentiality to build large area flexible and conformable robotic skin. I.

Material-Integrated Intelligent Systems - Technology and Applications, 2017

Endowing appliances with the capability of sensing and processing touch enables tactile interacti... more Endowing appliances with the capability of sensing and processing touch enables tactile interaction between electronic devices and the environment. E-skin organized as a set of multiple sensing components and integrated with a dedicated embedded electronic system can implement the communication link between e-skin and surroundings. Basing the analysis on a relevant application example (i.e. human prosthetics), the present study describes a system including an electronic skin and a stimulation unit. The overall system was validated and tested in eight healthy subjects, who were asked to recognize the shape, position and direction of a set of dynamic mechanical stimuli presented on the electronic skin. The results demonstrated that tactile information was successfully translated from a mechanical interaction applied on the e-skin into electrotactile patterns, which the subjects could recognize with a good performance. As the obtained results are promising, in this paper the challenging requirements for the integration of e-skin into prosthetic devices were assessed, mainly focusing on computational complexity of the embedded data processing unit.

Integration, Sep 1, 2018

Embedding electronics with tactile sensors may enable electronic skin to be applied in many domai... more Embedding electronics with tactile sensors may enable electronic skin to be applied in many domains such as prosthetics, robotics, industrial automation. The complexity of electronics from size and power consumption point of view represents the main barrier towards achieving goal. This paper provides the experimental characterization of dedicated front-end electronics for piezoelectric tactile sensing arrays. Aiming to decrease the hardware complexity, the designed circuits are based on the DDC112U and an FPGA Xilinx Spartan-6 devices. An experimental setup has been implemented to acquire the signal generated from a tactile sensor. Results validate the functionality of the proposed interface when the measured voltage and charge are analyzed in terms of the input force. Experimental characterization demonstrates the correctness of the results when the signal to noise and distortion (SINAD) ratio, and the effective number of bits (ENOB) have been analyzed.

Development of tactile sensing systems is motivated by the possibility of application in many dom... more Development of tactile sensing systems is motivated by the possibility of application in many domains such as robotics, prosthetics, and industrial automation. This paper provides a functionality assessment of an interface electronic circuit prototype for tactile sensing systems. The circuits are based on the DDC112U and an FPGA Xilinx Spartan-6. An experimental setup is carried out to measure the signals generated from a single tactile sensor. Experimental results validate the correct functionality of the proposed interface when the measured voltage and charge are analyzed in terms of the input force. Moving to the new system may pave the way towards the fully integrated SoC for the e-skin development.

Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb.... more Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb. To foster prosthesis embodiment and functionality, it is necessary to re-establish both volitional control and sensory feedback. Contemporary feedback interfaces presented in research use few sensors and stimulation units to feedback at most two discrete feedback variables (e.g., grasping force and aperture), whereas the human sense of touch relies on a distributed network of mechanoreceptors providing high-fidelity spatial information. To provide this type of feedback in prosthetics, it is necessary to sense tactile information from artificial skin placed on the prosthesis and transmit tactile feedback above the amputation in order to map the interaction between the prosthesis and the environment. This paper will provide a perspective on the use of distributed sensing and electrical stimulation systems for the restoration of the sense of touch in prosthetics.

We present an event-driven tactile sensing element that encodes both the absolute value of the in... more We present an event-driven tactile sensing element that encodes both the absolute value of the input force and its variation over time. It is based on the POSFET device and Leaky-Integrate and Fire neurons, connected by a transconductance amplifier; the proposed circuit exploits the advantages of the POSFET device, such as high integration scale, fast response, wide bandwidth and force sensitivity, as well as the advantages of event-driven encoding, such as low latency, low power dissipation, and high temporal resolution, coupled with redundancy reduction.

IEEE Transactions on Circuits and Systems I-regular Papers, Jun 1, 2017

We present a low-power compact circuit for the event-driven readout of tactile sensors. The taxel... more We present a low-power compact circuit for the event-driven readout of tactile sensors. The taxel is based on the POSFET device, a sensotronic unit where a piezo-electric material is deposited on the gate of a transistor, integrated with a Leaky-Integrate and Fire neuron circuit. This device encodes the applied force with trains of digital pulses, using the asynchronous Address Event Representation protocol. The instantaneous output spiking frequency is directly proportional to the force applied to the taxel. We show a full characterization of the device as well as quantitative measurements from a prototype fabricated on AMS CMOS 350-nm process. The taxel can reliably distinguish applied forces from 0.1 N up to 1.5 N.

Electronic skin can be integrated into a prosthetic device to endow the prosthesis with artificia... more Electronic skin can be integrated into a prosthetic device to endow the prosthesis with artificial cutaneous sensing, thereby partially restoring the sensory information lost due to an amputation. Non-invasive cutaneous electrostimulation transmits the tactile information sensed by the electronic skin on the prosthetic hand to the human brain, through the amputee's afferent nervous system. In this paper, our current benchtop prototype of a distributed sensing-stimulation system is presented, together with the envisaged high-fidelity solution which will be integrated into a real prosthetic hand.

IEEE Sensors Journal, Sep 15, 2017

In this paper, we propose a novel design approach for the interface electronics of piezoelectric ... more In this paper, we propose a novel design approach for the interface electronics of piezoelectric polymer tactile sensing systems. An interface electronics prototype based on commercial off-the-shelf (COTS) components having the same operating principle as the proposed approach has been fabricated. The system has been validated by using an experimental setup where electrical and electromechanical characterization are carried out. The interface electronics measures charge of about 0.15pC for applied forces as low as 12.5mN at the working frequency of 27Hz. The experimental average sensitivity of the system is 0.6pC/kPa in the frequency range from 10Hz to 250Hz. Long term goal is to miniaturize the interface electronics for the development of embedded tactile systems in prosthetic and robotic applications.

2018 IEEE International Symposium on Circuits and Systems (ISCAS), 2018

The lack of tactile sensation in current upper limb prostheses is the key limitation to enable mo... more The lack of tactile sensation in current upper limb prostheses is the key limitation to enable more intuitive use of the prosthesis and restore the functionality of the natural limb. Electronic skin in the form of tactile sensing arrays can be integrated onto the upper limb prosthetic device to record information about touch, given back to the amputee as a sensory feedback. This contribution focusses on the development of tactile sensing arrays based on PVDF-TrFE piezoelectric polymers. Both piezoelectric polymer sensors and metal contacts have been screen-printed on a transparent plastic foil. The geometric layout and size of the 4×4 array is suitable for prosthesis fingertips. Preliminary experimental validation of the skin patches is reported in this paper.

2018 IEEE International Symposium on Circuits and Systems (ISCAS), 2018

Closing the prosthesis control loop by providing tactile sensory feedback to the user is a key po... more Closing the prosthesis control loop by providing tactile sensory feedback to the user is a key point in research on active prosthetics as well as an often cited requirement of the prosthesis users.

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2015

The present research aimed at providing myoelectric prostheses with a comprehensive artificial cu... more The present research aimed at providing myoelectric prostheses with a comprehensive artificial cutaneous sensing to enable bidirectional communication. Preliminary experiments showed that subjects could recognize shape, position and direction of basic and more complex touches with a reasonable success rate. This sensory feedback system appears feasible and intuitive.

2017 New Generation of CAS (NGCAS), 2017

Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb.... more Modern prostheses aim at restoring the functional and aesthetic characteristics of the lost limb. To foster prosthesis embodiment and functionality, it is necessary to re-establish both volitional control and sensory feedback. Contemporary feedback interfaces presented in research use few sensors and stimulation units to feedback at most two discrete feedback variables (e.g., grasping force and aperture), whereas the human sense of touch relies on a distributed network of mechanoreceptors providing high-fidelity spatial information. To provide this type of feedback in prosthetics, it is necessary to sense tactile information from artificial skin placed on the prosthesis and transmit tactile feedback above the amputation in order to map the interaction between the prosthesis and the environment. This paper will provide a perspective on the use of distributed sensing and electrical stimulation systems for the restoration of the sense of touch in prosthetics.

Organic Electronics, 2016

This paper reports on a highly sensitive tactile sensor based on a floating gate organic transist... more This paper reports on a highly sensitive tactile sensor based on a floating gate organic transistor called Organic Charge Modulated FET coupled with a flexible piezoelectric polymer (namely a film of polyvinylene fluoride, PVDF). The proposed device is able to reliably transduce pressures as low as 300 Pa, thus opening up interesting perspectives for flexible and low-cost tactile sensors for e-skin applications.

2016 12th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME), 2016

Endowing appliances with the capability of sensing and processing touch enables tactile interacti... more Endowing appliances with the capability of sensing and processing touch enables tactile interaction between electronic devices and the environment. E-skin organized as a set of multiple sensing components and integrated with a dedicated embedded electronic system can implement the communication link between e-skin and surroundings. Basing the analysis on a relevant application example (i.e. human prosthetics), the present study describes a system including an electronic skin and a stimulation unit. The overall system was validated and tested in eight healthy subjects, who were asked to recognize the shape, position and direction of a set of dynamic mechanical stimuli presented on the electronic skin. The results demonstrated that tactile information was successfully translated from a mechanical interaction applied on the e-skin into electrotactile patterns, which the subjects could recognize with a good performance. As the obtained results are promising, in this paper the challenging requirements for the integration of e-skin into prosthetic devices were assessed, mainly focusing on computational complexity of the embedded data processing unit.

IEEE Sensors Journal, 2014

This paper presents the advanced version of novel piezoelectric oxide semiconductor field effect ... more This paper presents the advanced version of novel piezoelectric oxide semiconductor field effect transistor (POSFET) devices-based tactile sensing chip. The new version of the tactile sensing chip presented here comprises of a 4 × 4 array of POSFET touch sensing devices and integrated interface electronics (i.e., multiplexers, high compliance current sinks, and voltage output buffers). The chip also includes four temperature diodes for the measurement of contact temperature. Various components on the chip have been characterized systematically and the overall operation of the tactile sensing system has been evaluated. With new design, the POSFET devices have improved performance [i.e., linear response in the dynamic contact forces range of 0.01-3 N and sensitivity (without amplification) of 102.4 mV/N], which is more than twice the performance of their previous implementations. The integrated interface electronics result in reduced interconnections which otherwise would be needed to connect the POSFET array with off-chip interface electronic circuitry. This paper paves the way for CMOS implementation of full on-chip tactile sensing systems based on POSFETs.

IEEE Sensors Journal, 2013

The paper focuses on the manufacturing technology of modular components for large-area tactile se... more The paper focuses on the manufacturing technology of modular components for large-area tactile sensors, which are made of arrays of polyvinylidene fluoride (PVDF) piezoelectric polymer taxels integrated on flexible PCBs. PVDF transducers were chosen for the high electromechanical transduction frequency bandwidth (up to 1 kHz for the given application). Patterned electrodes were inkjet printed on the PVDF film. Experimental tests on skin module prototypes demonstrate the feasibility of the proposed approach and reveal the potentiality to build large area flexible and conformable robotic skin. I.

Material-Integrated Intelligent Systems - Technology and Applications, 2017