SUMMERY OF CAREER: 40 years experience in US companies, worked in the fields of piezoelectric transducers and sensors with multilayer design, MHz range medical/industrial ultrasonic transducers, wideband design, high sensitivity design, transient waveform prediction, FFT and IFFT programs combined with Mason model or KLM model, air ultrasonic transducers and parametric audio wave generation, all of which are based on wave related physics and work experience in similar physics in multi disciplinary fields such as microwaves, transmission lines, surface acoustic waves and interdigital transducers, optoelectronics, semiconductor lasers have lead to many creative ideas mainly on transducer designs as seen in the granted patens. Among these, recent unique outstanding field is multiple of new designs of impedance matching for ultrasonic transducers/sensors for human body or water and air/gas, and he developed lots of new products, granted 57 US patents and many publications (as seen in Google scholar https://scholar.google.com/citations?user=vTjU9uoAAAAJ&hl=en where it is recorded as 85 papers authored).
EXPERIENCE / SERVICE : After decades of work in high technology production companies, for recent years, he worked as a consultant for several companies on design of ultrasonic transducers for application of medical imaging, flow velocity measurement, heart movement monitoring, eye motion detection and super directive audio wave generation from parametric effect of air ultrasound, where he used MATLAB models in simulations which he wrote from basic equations and with experimental validations. Number of unique concepts were created, where new matching layer using mass-spring resonator which is combination of very thin layers (1/20 -1/30 lamda ) of polymer-metal layers providing wideband and high sensitivity replacing traditional quarter wavelength layer leading to low cost reproducible production process, polymer-metal multilayer absorbers with feature of numerically designed structure and high reproducibility replacing traditional powder/binder, internal matching layer inside of protection metal layer, special matching layer for high power focused ultrasonic transducers for abrasion of internal organ used for non-invasive surgery, multiple hole matching layer or matching structure of protection panel for metal-PZT or cylindrical PVDF air transducers.
800 MATLAB programs are available which are used to predict performance of ultrasonic transducers / sensors including arbitrarily complicated multilayer, multilayer matching backing layers including epoxy and electrode effects, determination of composite or single plate piezo-material parameters using parameter fitting method (comparison of impedance spectrum for measured and calculated curves), near field to far field directivity used for phase array transducers, electrical matching network and cable effect modifying/enhancing performance of ultrasonic transducers with advantageous additional matching network enhancing sensitivity by one order, design of PZT, PVDF or PVDF/TrFE copolymer ultrasonic transducers, cylindrical PVDF film ultrasonic air transducers with protection cage effect with impedance matching, patented corrugated PVDF film with large area high acoustic pressure transducers, etc.
Measurement equipment are available for consulting service, which are impedance analyzer, network analyzer, LCR meter, pulse generator-amplifier, function generators, variable gain/bandwidth amplifier, oscilloscopes, calibrated microphone up to 110 kHz. Full spectrum of circuit components are available so that building test circuits are possible. Fabrication machines and tools, observation microscope, structural materials and chemicals for etching or plating are available, all of which are served for customized experiments depending on customer's need.
Unique and reliable way of prediction of transducer performance is done by (1) measurements of acoustic velocity and impedance to obtain reliable parameters used for modelling (2) determine parameters of piezoelectric material from comparison between measured impedance spectrum and calculated curve (parameter fitting) - usually vendor's parameters are for general applications and are different at the frequency of specific use, (3) making multilayer models using the reliable parameters for design of multi-layer transducers, which are used for prediction of sensitivity performance with frequency response curves, transient waveform prediction (Matlab FFT -iFFT) and analysis of radiation field, and angular dependence of sensitivity possible.
