Showing papers in "Sensors and Actuators A-physical in 2008"

Fibre Bragg gratings in structural health monitoring—Present status and applications

Abstract: In-service structural health monitoring (SHM) of engineering structures has assumed a significant role in assessing their safety and integrity. Fibre Bragg grating (FBG) sensors have emerged as a reliable, in situ, non-destructive tool for monitoring, diagnostics and control in civil structures. The versatility of FBG sensors represents a key advantage over other technologies in the structural sensing field. In this article, the recent research and development activities in structural health monitoring using FBG sensors have been critically reviewed, highlighting the areas where further work is needed. A few packaging schemes for FBG strain sensors are also discussed. Finally a few limitations and market barriers associated with the use of these sensors have been addressed.

Electromagnetic generator for harvesting energy from human motion

Abstract: This paper presents an electromagnetic based generator which is suitable for supplying generating power from human body motion and has application in providing energy for body worn sensors or electronics devices. A prototype generator has been built and tested both by a shaker at resonance condition and also by human body motion during walking and slow running. The experimental results will show that the prototype could generate 300 μW to 2.5 mW power from human body motion. The measured results are analyzed and compared with the theoretical model.

Fibre-optic sensor technologies for humidity and moisture measurement

Abstract: A review of the use of fibre-optic sensor technologies for humidity sensing is presented. The paper first provides a brief overview on the basic concept of what is meant by humidity and on conventional detection methods. This is followed by an extensive review on the various fibre-optic techniques reported for humidity sensing, covering both intrinsic and extrinsic sensor configurations.

Piezoelectric multifrequency energy converter for power harvesting in autonomous microsystems

Abstract: A multifrequency mechanoelectrical piezoelectric converter intended for powering autonomous sensors from background vibrations is presented. The converter is composed of multiple bimorph cantilevers with different natural frequencies, whose rectified outputs are fed to a single storage capacitor. The structure of the converter, description of the operation, and measurement data on the performances are reported. Experimental results show the possibility of using the converter with input vibrations across a wideband frequency spectrum, improving the effectiveness of the overall energy conversion over the case of a single converter. The converter was used to supply power to a battery-less sensor module that intermittently reads the signal from a passive sensor and sends the measurement information via RF transmission, in this way forming an autonomous sensor system with improved measure-and-transmit rate.

An electromagnetic micro power generator for wideband environmental vibrations

Abstract: This paper presents a wideband electromagnetic vibration-to-electrical micro power generator. The micro generator is capable of generating steady power over a predetermined frequency range. Power is generated by means of the relative motion between a magnet and coils fabricated over resonating cantilevers through electromagnetic induction. The reported generator covers a wide band of external vibration frequency by implementing a number of serially connected cantilevers in different lengths resulting in an array of cantilevers with varying natural frequencies. The device generates 0.4 μW of continuous power with 10 mV voltage in an external vibration frequency range of 4.2–5 kHz, covering a band of 800 Hz.

Pressure sensor from a PVDF film

Abstract: A new low-cost polymer pressure sensor has been developed. A piezoelectric polyvinylidenefluoride (PVDF) film is used in this sensor as the sensing element. The design of the sensor and the manufacturing are described in detail. The properties of the sensor have been investigated experimentally. The cross-sensitivity to temperature and humidity and the response time were measured and changes of the characteristic curve due to aging were investigated. The influence of different chemicals on the output signal of the pressure sensor are reported and discussed.

Flexible polymeric dry electrodes for the long-term monitoring of ECG

Abstract: In this paper, we present a novel polymeric dry electrode that (1) changes its shape in a way that supports the electrode's contact with the skin and (2) that does not cause skin irritations or allergic reactions For a polymeric substrate of electrodes, we have used the elastomer poly(dimethylsiloxane), which is known to be inexpensive, biocompatible, and amenable to micro-molding, and to have excellent gas and water permeability We have established a process by which one can deposit a metal layer on the PDMS substrate, etch the electrode patterns chemically and with good resolution, and package the electrode so that it is easily wearable on the forearm We measured the impedance according to the frequency change and compared the results with those of Ag/AgCl electrodes Afterward, we measured the ECG signal and investigated possible artifacts caused by motion For the feasibility of long-term monitoring, we examined the influence of surface electrodes on the skin after 7 days of ECG monitoring In conclusion, our PDMS-based dry electrode measured the ECG signals with comparatively good fidelity, but showed better skin compatibility after long-term tests We expect that our method for the production of PDMS-based dry electrodes will be broadly applicable to the field of ubiquitous biosignal monitoring

A micro-robot fish with embedded SMA wire actuated flexible biomimetic fin

Abstract: A flexible biomimetic fin propelled micro-robot fish is presented. Fish muscle and the musculature of squid/cuttlefish fin are analyzed firstly. Since the latter one is easier to be realized in the engineering field, it is emulated by biomimetic fin. Shape memory alloy (SMA) wire is selected as the most suitable actuator of biomimetic fin. Elastic energy storage and exchange mechanism is incorporated into the biomimetic fin for efficiency improvement. Furthermore the bending experiments of biomimetic fin were carried out to verify the original ideas and research concepts. Thermal analysis is also conducted to find a proper actuation strategy. Fish swimming mechanism is reviewed as the foundation of the robot fish. A radio frequency controlled micro-robot fish propelled by biomimetic fin was built. Experimental results show that the micro-robot fish can swim straight and turn at different duty ratios and frequencies. Subcarangiformand carangiform-like swimming modes were realized. The maximum swimming speed and the minimum turning radius reached 112 mm/s and 136 mm, respectively. © 2008 Elsevier B.V. All rights reserved.

Integrated power harvesting system including a MEMS generator and a power management circuit

Abstract: This paper presents a novel ambient energy scavenging system for powering wireless sensor nodes. It uses a MEMS generator and an ASIC power management circuit. The system is created as a System on a Package with all components fabricated entirely using microfabrication techniques. Its performance is compared with standard approaches using a resistive load or discrete Schottky diodes. The electromechanical transduction is performed using the piezoelectric effect of aluminium nitride thin films. The reported experimental results prove the possibility of exploiting very low amplitude signals delivered by the generator for charging a storage capacitor. It is also shown that a system of 5 mm 3 can endlessly power a simple wireless sensor node; while a lithium polymer thin film battery of the same volume can do so only for less than 2 months.

A self-sensing dielectric elastomer actuator

Abstract: A novel self-sensing method based on the dielectric elastomer (DE) actuator/sensor, was successfully developed and evaluated in order to extract accurate displacement information during the actuation process without using any additional sensing device. The proposed self-sensing method is based on a capacitance characteristic of a DE actuator. The DE actuator with a serial external resistor can serve as an electrical high-pass filter. The voltage gained using the high-pass filter, which is virtually built by the DE, varies due to the change of overall capacitance when the DE actuator is expanded electro-mechanically. To realize actuating and sensing simultaneously with a DE actuator, we used a modulation technique to mix signals, which have a low frequency signal for actuating and a high frequency with small amplitude for sensing. Several experiments were performed to verify the usability of the proposed self-sensing method. The results showed a fine resolution and an excellent correlation with the displacements measured by a laser displacement sensor.

A wearable yarn-based piezo-resistive sensor

Abstract: Smart textiles using fabric-based sensors to monitor gesture, posture or respiration have been exploited in many applications. Most of fabric-based sensors were fabricated by either coating piezo-resistive materials on a fabric or directly knitting conductive fibers into fabrics. Obviously, structures of textiles, including yarn structure and fabric structure, will affect the performances of sensors. However, researches on the effects of the structures have not been explored yet. In this paper, yarn-based sensors were fabricated by using piezo-resistive fibers, elastic, and regular polyester fibers. Single and double wrapping methods were employed to fabricate the yarn-based sensors. Performances of the designed yarn-based sensors were evaluated by measuring their resistance changes under variable loading. It is shown that slippage occurs between the piezo-resistive fibers and the core fibers. The relationship of the resistance versus the strain cannot be described as a linear function and should be modeled as a second order equation. Due to the symmetric structure, the double wrapping yarn could resist the slippage and higher linearity in the resistance curve can be provided. Thus it can be served as a better sensing element. The study also investigates the issue of the twist per meter (TPM) and finds that there are no significant effects for using different TPM. Finally, experiments were conducted on a respiration monitoring system to prove the feasibility of the yarn-based sensors and the results demonstrate that the yarn-based sensor can track the respiratory signals precisely.

Design and fabrication of MEMS thermoelectric generators with high temperature efficiency

Abstract: For MEMS devices with power consumption in the range of micro-watts, thermal energy harvesting becomes a viable candidate for power supply. This paper describes a multipurpose platform to fabricate thermoelectric generators in a combined surface and bulk micromachining process. The thermocouples are deposited by thin-film processes with high integration density on the wafer surface. To provide a large thermal contact area, the heat flow path is perpendicular to the chip surface (cross-plane) and guided by thermal connectors. One thermocouple junction is thermally connected via electroplated metal stripes to the heat source and thermally insulated to the heat sink by a cavity in the wafer substrate. Simulations show that approximately 95% of the entire temperature difference over the device is located between the two thermocouple junctions. Power factors of 3.63 × 10 −3 μW mm −2 K −2 and 8.14 × 10 −3 μW mm −2 K −2 can be achieved with thermopiles made of Al and n-poly-Si or p-Bi 0.5 Sb 1.5 Te 3 and n-Bi 0.87 Sb 0.13 , respectively. Measurements of fabricated devices show a linear output voltage of 76.08 μV K −1 per thermocouple and prove the feasibility of the concept.

An electrochemical intraocular drug delivery device

Abstract: A microelectromechanical systems (MEMS) drug delivery device is investigated for the treatment of incurable ocular diseases. Unlike conventional ocular drug delivery devices, this MEMS device is capable of being refilled, features electronic control of the drug regimen, and enables targeted intraocular drug delivery. The refillable design permits long-term drug therapy and avoids repetitive surgeries. Electronic control of dosing is achieved by using electrolysis-actuated pumping to deliver pharmaceuticals directly to the intraocular space. A flexible Parylene transscleral cannula allows targeted delivery to tissues in both the anterior and posterior segments of the eye. This electrochemically driven drug delivery device was demonstrated to provide flow rates suitable for ocular drug therapy (pL/min to μL/min). Both continuous and bolus drug delivery modes were performed to achieve accurate delivery of a target volume of 250 nL. An encapsulation packaging technique was developed for acute surgical studies and preliminary ex vivo drug delivery experiments in porcine eyes were performed.

Modelling the dynamics of a MEMS resonator : simulations and experiments

Abstract: Nonlinearities in MEMS silicon resonators are caused by different effects. Depending on the resonator layout, different nonlinearities may be dominant in the resonator response. Based on experimental results, a modelling approach is proposed to arrive at a nonlinear dynamic model that potentially captures the observed behaviour. Apart from the model, consisting of a mechanical and an electrical (measurement) part, the effect of thermal noise is also estimated. With the proposed model, a quantitative match between the simulation and experimental results is established such that a good starting point is achieved for a more thorough modelling procedure.

In-line fiber Fabry-Perot refractive-index tip sensor based on endlessly photonic crystal fiber

Abstract: This paper, for the first time to the best of our knowledge, presents a novel fiber-optic refractive-index sensor which is based on an intrinsic Fabry-Perot interferometer (IFPI) formed by a section of endlessly single-mode photonic crystal fiber (EPCF) and conventional single-mode fiber. Such an IFPI sensor has the advantages of easy fabrication, low joint and transmission losses, low-cost and good fringe visibility due to the use of the EPCF. This miniature fiber-optic sensor is demonstrated for the measurement of the refractive index change of glycerin solution by measuring its fringe visibility change solely. The experimental data agree well with the theoretical results and the refractive-index resolution and repeatability of ∼2 × 10−5 and ±0.5%FS in the linear operating range, are achieved. In addition, such a sensor can be used as an excellent temperature sensor with a cavity-length-temperature sensitivity of 4.16 nm/°C and repeatability of ±0.15%FS when tested from 20 °C to 100 °C. Therefore, simultaneous measurement of refractive index and temperature can be realized by determination of the fringe visibility and the cavity length change of such a PCF-based IFPI, respectively, providing a practical way to measure refractive index with self-temperature compensation.

In-plane MEMS-based nano-g accelerometer with sub-wavelength optical resonant sensor

Abstract: We have successfully demonstrated a series of results that push the limits of optical sensing, acceleration sensing and lithography. Previously, we built some of the most sensitive displacement sensors with displacement sensitivities as low as 12 fm / Hz at 1 kHz. Using reference detection circuitry in conjunction with correlated double sampling methods, we lowered the 1/f noise floor to 10 mHz, hence improving the detection limit at low frequencies (10 mHz) by 77 dB to 50 fm / Hz . We converted these highly sensitive displacement sensors to highly sensitive acceleration sensors through a direct mass integration processes. Our accelerometers have resonant frequencies as low as 36 Hz and thermal noise floors as low as 8 nG / Hz (where 1 G = 9.8 m/s2). We have pushed the limits of shaker table experiments to independently verify acceleration measurements as low as 10 μ G / Hz . Direct measurements with our integrated sub-wavelength optical nano-grating accelerometers have shown device sensitivities of 590 V/G and noise floors corresponding to 17 nG / Hz (at 1 Hz).

Demonstration of cortical recording using novel flexible polymer neural probes

Abstract: We present the fabrication, characterization, use in cortical recording and histological results of a flexible implantable neural probe. The microfabricated device is implemented in polyimide and platinum providing mechanical flexibility, high quality electrical characteristics and excellent biocompatibility. Two layers of platinum electrodes are used which greatly reduces the size of the neural probes thereby limiting the insertion damage. The quality of the individual recording sites was characterized using impedance spectroscopy. In recording experiments, acute in vivo measurements were performed in the mouse cortex. Local field potential, single- and multi-neuron activities were simultaneously recorded. We demonstrate using immunohistochemistry techniques a study of the inflammation at the neural probe implantation site. We show that the major advantage of using polymer probes over silicon probes is the reduced damage due to insertion and probe-brain compliance mismatch.

An integrated flexible temperature and tactile sensing array using PI-copper films ☆

Abstract: This paper presents the design, fabrication and measurement of a flexible 8 × 8 temperature and tactile sensing array which will be used as the artificial skin for robot applications. The temperature and tactile sensing elements are heterogeneously integrated on a flexible copper-PI film using micromachining techniques. The tactile sensing elements are formed by dispensing conductive polymer on the pre-defined interdigital copper electrodes. This novel fabrication method can effectively reduce the crosstalk between each sensing element. The strategy and the verification for reducing crosstalk currents are described. The mechanical and electrical properties of tactile sensing elements are measured. Also, discrete temperature sensor chips are employed as the temperature-sensing cells. Scanning circuits are implemented. Finally, measured temperature and tactile images have been successfully obtained by using the integrated 8 × 8 sensing arrays. The flexible sensor arrays are bendable down to a 4-mm radius without any degradation in functionality.

On the wet etching of Pyrex glass

Abstract: This paper addresses a commonly raised question regarding wet etching of Pyrex glass: “How are the defects on the glass generated during etching process while most of the masking materials are chemically inert in the etching solution?” The response to this question relies in controlling the residual stress in the masking layer (its value, gradient and nature: compressive or tensile) and controlling the hydrophobicity of the mask surface. With this response, the solution for achieving a suitable process can be easily set up: a low stress masking layer (preferably performed by successive depositions) and a hydrophobic surface of the masking layer (easily achieved, for example by hard baking of the photoresist masking layer). Nevertheless, these factors must be correlated with a correct selection of the glass material (low content of oxides that gives insoluble products after the reaction with the etching solution) and a fast etch rate (achieved using highly concentrated hydrofluoric acid). The best reported results in the literature are analyzed for this perspective.

An advanced reactive ion etching process for very high aspect-ratio sub-micron wide trenches in silicon

Abstract: This paper reports on a practical modification of the two-step time-multiplexed plasma etching recipe (also known as the Bosch process) to achieve high aspect-ratio sub-micron wide trenches in silicon. Mixed argon and oxygen plasma depassivation steps are introduced in between the passivation and etching phases to promote the anisotropic removal of the passivation layer at the base of the trench. Argon does not chemically react with polymers and silicon and removes the passivation layer only by physical sputtering. Therefore, it results in a highly anisotropic polymer etching process. This recipe can be easily integrated on conventional ICP equipment and the scalloping on the trench sidewall can potentially be reduced in size to less than 50 nm. To clean up all the passivation residues, a short oxygen plasma step is also added at the end of the cycle that effectively improves the uniformity of the etching profile over various opening sizes. Excellent anisotropy of the inserted argon depassivation step facilitates narrow trenches down to 130 nm wide and gap aspect-ratios as high as 40:1, extending the application of deep reactive ion etching (DRIE) processes into a new broad regime.

A large vertical displacement electrothermal bimorph microactuator with very small lateral shift

Abstract: This paper reports a novel electrothermal actuator design that can generate large vertical displacements with almost no lateral shift. The lateral-shift-free (LSF) piston motion is achieved by using a unique three-bimorph actuation mechanism. Both micromirrors and microlens holders based on this new actuator design have been fabricated using a combined surface- and bulk-micromachining process. A 0.62 mm vertical displacement is measured at only 5.3 V for a fabricated 0.8 mm by 0.8 mm micromirror, and both the lateral shift (10 μm) and tilting angle (0.7°) are very small in that full vertical displacement range. The measured resonant frequency of the vertical motion mode is about 0.5 KHz. The thermal response time is about 25 ms.

Self-powered circuit for broadband, multimodal piezoelectric vibration control

Abstract: Vibration control using piezoelectric actuators has experienced a strong development these last years. Particularly, non-linear techniques have been proven to be low-cost and efficient ways of damping, with self-powering capabilities. This paper deals with one of these methods, the so-called self-powered synchronized switch damping on inductor (SSDI). Its principles rely on switching intermittently the piezoelement on a resonant circuit. Particularly, it is proposed here a new self-powered device that enhances the broadband nature of the self-powered SSDI. The principles of the circuit are to disable the switching event unless a particular condition is fulfilled. Experimental results show that such a circuit significantly improves the multimodal control abilities of the self-powered SSDI techniques without any external power supply requirements.

Biodegradable polymer needle with various tip angles and consideration on insertion mechanism of mosquito's proboscis

Abstract: The present paper proposes a fabrication method of microneedles with various tip angles made of biodegradable polymer (polylactic acid, referred to herein as PLA) It was confirmed by the finite element method (FEM) simulation that the stress concentration occurs more severely at the tip area, as the needle becomes thin, and the tip angle becomes sharp Photomasks for silicon cavities (negative dies for micromolding) with various tip angles are designed The fabrication process involves etching a groove on the surface of a silicon die, molding the polymer into this groove, and then releasing it The resistance force during inserting a fabricated needle to an artificial skin of silicone rubber was investigated Effectiveness of sharp tip angle and thin shank for easy insertion is confirmed Imitating the mosquito's proboscis, the effectiveness of vibrating needle, and giving surface tension to the object surface was also confirmed The combined needles like the mosquito's proboscis, which are composed of a central straight needle and two outer jagged ones, are assumed The effectiveness of these needles for easy insertion is three dimensionally investigated by the FEM simulation Based on the result, the insertion mechanism of the mosquito's proboscis is discussed

Structural and functional properties of screen-printed PZT–PVDF-TrFE composites

Abstract: Thick films of 0–3 composites of lead–zirconate–titanate (PZT) particulate and polyvinylidene-trifluoroethylene (PVDF-TrFE) copolymer have been produced by screen-printing on indium–tin-oxide (ITO)-coated glass substrates. The microstructure was investigated using scanning electron microscopy and X-ray diffraction. The dependences of the dielectric properties of the composites on PZT volume fraction are reported and analyzed in terms of an analytical model. The pyroelectric properties were determined using dynamical experimental setups, and are given in terms of pyroelectric coefficient and figures of merit. The piezoelectric response was investigated as a function of the PZT volume fraction using a laser vibrometer. The piezoelectric charge coefficient, d 33,eff , is shown to exhibit a minimum at a PZT volume fraction of 40% which arises from the piezoelectric charge coefficients of the pure constituents being of opposite sign. It is thought that screen-printing of these composites constitutes a cost-effective way of producing structured functional thin films for pyroelectric and piezoelectric applications.

A neural networks based model for rate-dependent hysteresis for piezoceramic actuators

Abstract: A method for the identification of the rate-dependent hysteresis in piezoceramic actuators is proposed. In this approach, both a so-called generalized gradient of the output with respect to the input of the hysteresis and the derivative of the input that represents the frequency change of the input are introduced into the input space. Then an expanded input space is established. Thus, the multi-valued mapping of the rate-dependent hysteresis can be transformed into a one-to-one mapping based on the expanded of the input space. In this case, the neural network method can be applied to the modeling of the rate-dependent hysteresis. Finally, the experimental results are presented to illustrate the performance of the proposed approach.

Construction and performance test of a novel polarization sensor for navigation

Abstract: Navigation technology is an essential ability for the survival and development of animal and human. Navigation sensor plays a key role in exploration, emergency, precision-guided weapons, ship and aircraft navigation and satellites positioning system. The desert ant Cataglyphis is able to explore its desert habitat for hundreds of meters while foraging and return back to its nest precisely and on a straight line. For deriving direction information, this animal uses the pattern of polarized light in the sky that arises due to scattering of sunlight in the atmosphere. The polarization sensitivity mechanisms of the ant's compound eye are analyzed. The work principle of the sensor is discussed. A novel bionic navigation sensor is constructed. And the optic electric structure and the circuits are given. A performance test platform is designed and set up. The character of the dark field and uniform light field are investigated, the static performance about sensitivity, precision are tested in detail. And the non-linearity error is less than 0.0853% FSO (full-scale output), and the repeatability error with 0.0233% FSO is achieved. The outdoor experiment is performed under different skylight condition. And the worst angle output error within ± 0.2° is achieved. The results indicate the novel navigation sensor is with high precision and robustness.

Long period grating-based humidity sensor for potential structural health monitoring

Abstract: This paper reports the work on the development of novel humidity sensors using long period grating (LPG) technology in an optical fibre. The sensors are created through coating a thin layer of polyvinyl alcohol (PVA), whose refractive index varies as a function of humidity level, onto an LPG. The LPG written in a single mode optical fibre provides a means to change the coupling between the core and cladding modes thus to induce a wavelength shift in the attenuation bands of the transmission spectrum of the optical sensor device created. In this work different sensor configurations were created by coating various LPGs and then characterizing the resulting sensor performance. The work carried out has shown that, compared to the more familiar fibre Bragg grating (FBG)-based humidity sensors, LPG sensors show higher measurement sensitivity, with more relaxed requirements for the coating thickness and uniformity, with the potential for their development as chemical sensors through optimization of the design of the coating materials chosen. In this research, the sensors which were designed and fabricated were created for future applications in determining moisture ingress in a range of concrete materials when subjected to various environmental conditions.

Design of a magnetostrictive (MS) actuator

Abstract: Several advanced technologies are introduced in automotive applications. Higher energy density and dynamic performance are demanding new and cost-effective actuator structures. Magnetostriction (MS), change in shape of materials under the influence of an external magnetic field, is one of the advanced technologies. Good understanding of specific design constrains is required to define and optimize a magnetostrictive actuator. This paper presents parametrical analysis with magnetic simulation of a magnetostrictive actuator. Proposed actuator has been designed, and the performance has been evaluated on experimental rig. Strain, elongation of the shaft, of 1000 ppm at 10 A and a blocked force over 4500 N has been achieved with shaft of 8 mm diameter, made of Terfenol- D . Furthermore, the effect of pre-stress of the Terfenol- D shaft has been evaluated experimentally. The study shows that excellent features can be obtained by magnetostrictive materials for many advanced applications.

Fabrication of micro sensors on a flexible substrate

Abstract: Flexible micro temperature and humidity sensors on parylene thin films were designed and fabricated using a micro-electro-mechanical-systems (MEMS) process. Based on the principles of the thermistor and the ability of a polymer to absorb moisture, the sensing device comprised gold wire and polyimide film. The flexible micro sensors were patterned between two pieces of parylene thin film that had been etched using O 2 plasma to open the contact pads. The sacrificial Cr spacer layer was removed from the Cr etchant to release the flexible temperature and humidity sensors from the silicon substrate. Au was used to form the sensing electrode of the sensors while Ti formed the adhesion layer between the parylene and Au. The thickness of the device was 7 ± 1 μm, so the sensors attached easily to highly curved surfaces. The sensitivities of the temperature and humidity sensor were 4.81 × 10 −3 °C −1 and 0.03 pF/%RH, respectively. This work demonstrates the feasibility and compatibility of thin film sensor applications based on flexible parylene. The sensor can be applied to fuel cells or components that must be compressed.

Photovoltaic properties of the organic-inorganic photodiode based on polymer and fullerene blend for optical sensors

Abstract: Inorganic–organic photodiode was fabricated with blend single layer as well as sandwich structure, using p-Si and poly(2-methoxy-5-(20-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV):fullerene-C60 blend. Electronic parameters such as barrier height, diode ideality factor, series resistance and shunt resistance were determined from the I–V characteristic in the dark of p-Si/C60:MEH-PPV diode and were found to be 0.75 eV, 1.36, 6.26 × 105 Ω, 1.40 × 1010 Ω, respectively. The interface state density and time constant of p-Si/C60:MEH-PPV diode were determined to be 2.55 × 1011 eV−1 cm−2 and 1.81 × 10−6 s, respectively. The photoconductivity sensitivity and responsivity values of the diode were found to be 8.16 × 10−6 S m/W and 1.63 × 10−2 A/W, respectively. The p-Si/C60:MEH-PPV diode indicates a photovoltaic behaviour with a maximum open circuit voltage Voc of 130 mV and short-circuit current Isc of 24.5 nA. The photocurrent of the device was found to be 2.94 μA and photoconductivity mechanism of the p-Si/C60:MEH-PPV diode indicates the existence of continuous distribution of trap centres. It is evaluated that the p-Si/C60:MEH-PPV photovoltaic device can be operated as a heterojunction photodiode.