Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno

Hylke Broer Akkerman

Arno Willem Frederik Volker

Paul Louis Maria Joseph Van Neer

Gerwin Hermanus Gelinck

Antonius Maria Bernardus Van Mol

Petrus Cornelis Paulus Bouten

Michiel Peter Oderwald

Arthur Perry Berkhoff

Arjen Amelink

Albert Jos Jan Marie Van Breemen

Ahmed Fawzy

Venkata Krishna Pradeep Panditha

Joris Franciscus Johannes De Riet

Raghu Kishore Pendyala

A system and method for contact-based spatial frequency domain imaging. A medium to be imaged is contacted by a sheet comprising an array of lighting elements generating illumination light patterns illuminating the medium, and comprising an array of sensor elements measuring spatially resolved images of resulting light patterns reflected back after interaction of the illumination light patterns with the medium. The lighting elements generate illumination light patterns that are spatially modulated in light intensity along a surface of the illuminated medium according to a respective different spatial frequency. A set of spatially modulated images is determined based on the measured resulting light patterns caused by the different illumination light patterns. An image of the medium can be generated based on a combination of the spatially modulated images.

Spatial frequency domain imaging system and method

An ultrasonic transducer is described that includes a stack of at least two membranes attached to a substrate. An electric circuit is coupled to the electrodes with a controller configured to apply a first electric signal to a first electrode on the first membrane, and a different, second electric signal to a second electrode on the second membrane. The first and second electric signals are configured to apply a varying voltage between the first electrode and the second electrode during a respective vibration cycle of the membranes. The first electrode on the first membrane is configured to interact with the second electrode on the second membrane by a varying electrostatic force during the respective vibration cycle depending on the varying voltage.

Ultrasonic transducer with stacked membranes

An acoustic device () comprises an array of acoustic membranes () formed on a foil (). Each of the acoustic membranes () is configured to vibrate at a resonance frequency (Fr) of the acoustic membranes () for generating respective acoustic waves (W,W,W,W). Relative phases (ΔΦ) are determined at which the acoustic membranes () are actuated for generating a predetermined interference pattern (C) between the acoustic waves (W,W,W,W). A lamb wavelength (As) is determined of lamb waves (Ws) at the resonance frequency (Fr) travelling through intermediate sections (lOi, lOj) of the foil () between adjacent acoustic membranes (). Distances (X,X) of the intermediate sections () between the adjacent acoustic membranes () in the layout are determined in accordance with the relative phases (ΔΦ) and the lamb wavelength (λs) for having the lamb waves (Ws), generated by one acoustic membrane (), arrive in phase with an adjacent acoustic membrane ().

Optimization of an acoustic membrane array

A device () and method for adhering by suction to a target surface (). The device has a substrate () with a contact surface () for contacting the device () to the target surface (). A plurality of pocket () are formed by respective pocket surfaces () concavely extending into the contact surface (). The pockets () have an open side () facing and being closed off by the target surface (). A flexible membrane () forms at least part of the pocket surface (). An actuator () is configured to actuate the flexible membrane (). A one-way valve () through the pocket surface () is configured to direct a contents of the pocket () via the one-way valve () to an environment ().

Configurable adhesive device and method

A method and system for controlling an array of piezoelectric transducers (). Respective driving signals (Vn) are applied to the transducers. The driving signals (Vn) comprise an alternating component (A) oscillating at one or more driving frequencies to cause corresponding vibrations in the transducers for generating acoustic waves (Wn). One or more of the driving signals (Vn) are offset by a respective bias voltage (Bn). The bias voltage (Bn) is controlled to reduce a difference in resonance frequencies between the transducers. To eliminate any remaining difference, the alternating component (A) to at least a subset of the transducers () is periodically reset. In this way the phases of the resulting acoustic waves (W,W) can be synchronized.

Control of a piezoelectric transducer array

A foldable thin film device assembly is provided comprising: a flexible thin film device with a thickness smaller than 50 micrometer. The thin film device has a stack of electroactive layers formed on a substrate. A protective inorganic capping layer caps the stack of electroactive layers and a backside elastomeric layer backs the flexible thin film device. A frontside transparent elastomeric layer covers the flexible thin film device, and backside and frontside flexible layers are dimensioned to mechanically form a neutral line for the protective inorganic layer. The elastomeric material has a Young's modulus smaller than 100 MPa smaller than 100 MPa and thickness larger than 100 micron, with a flexural rigidity equal or larger than the thin film device.

Growing community of inventors

Rosmalen, Netherlands

Hylke Broer Akkerman