Steve X. Dai

Design and Evaluation of Identifiable Key-Click Signals for Mobile Devices

As touch based input becomes more popular in mobile devices, there is an increasing need for haptic feedback on key-less input surface. Four experiments were conducted to design and evaluate identifiable emulated key-click signals using a piezoelectric actuator. Experiments I and II assessed the information transmission capacity for the amplitude, frequency, and number of cycles of raised cosine waveforms used to drive the piezo actuators under fixed- and roving-background conditions, respectively. Experiment III estimated the total information transfer for all three parameters. The results were used to reduce the number of stimulus alternatives in the key-click signal set with the goal to achieve perfect identification performance. Experiment IV verified that up to 5 to 6 identifiable key-click signals could be achieved with the experimental setup. The present study outlines an information theoretic approach to conducting identification experiments to guide the design of and to evaluate a perfectly identifiable stimulus set. The methodology can be applied to other applications in need of perceptually identifiable stimulation patterns.

Effects of alumina on devitrification kinetics and mechanism of K2O-CaO-SrO-BaO-B2O3-SiO2 glass

Effects of alumina on the devitrification kinetics and mechanism of a low-dielectric K2O–CaO–SrO–BaO–B2O3–SiO2 glass powder have been investigated. Crystalline phases including cristobalite (SiO2) and pseudowollastonite [(Ca, Ba, Sr)SiO3] are formed during the firing of the pure glass. With added alumina content greater than a critical value, e.g., 10–20 vol% at 900–1000°C, the above crystalline phases are completely prevented but anorthite [(Ca, Sr, Ba)Al2Si2O8] is formed. This result is attributed to the dissolution of alumina into the glass. The dissolution changes the composition of the glass to become aluminum-rich, and the dissolution kinetics of alumina into the glass is far too rapid compared with the formation of cristobalite and pseudowollastonite. The crystallization kinetics of anorthite follows the analysis of the Avrami equations, and the results show an apparent activation energy close to that of the Al–O bond strength, suggesting a reaction-controlled kinetics.

Add Ceramic “MEMS” to the Pallet of MicroSystems Technologies

Just as the 40+ years of technology developments associated with the electronic application of semiconductor fabrication processes is “morphing” into a micro-electro- mechanical systems (MEMS) technology in the past dozen years or so, so it seems may the “mature” multilayer ceramic fabrication technology associated with capacitor components and interconnect substrates for the integrated circuit industry, be morphed into MEMS – microsystems technology applications. This paper highlights work underway in Motorola Labs aimed at exploring the potential to develop 3D multilayer ceramic structures to integrate (monolithic and hybrid) multiple functions to create microsystems for wireless, energy and life science applications. By multiple functions, we refer to the ability for a microsystem to perform electronic, fluidic, thermonic, photonic and mechatronic (or actuator) based functions. Current capabilities of the multilayer ceramic materials and processes to achieve integrated functionalities for wireless applications will be described including the development of a new dielectric enabling increased performance for wireless applications. Also to be highlighted will be exploratory microscale fuel cell prototypes exploiting advances in the multilayer ceramic lamination and feature forming technologies enabling the insertion of 3D microchannels for microfluidic functions. These prototypes also feature the ability of the technology to provide thermonic functionality for microreactor devices. Feasibility of a light source that can be integrated into the technology platform hinting at photonic applications will be described. Many materials science and engineering advancements are needed to achieve the potential of this “old” but newly “morphing” technology and some of these will be noted.

Sintering of a crystallizable K2O-CaO-SrO-BaO-B2O3-SiO2 glass with titania present

Crystallization and reaction kinetics of a crystallizable K 2 O-CaO-SrO-BaO-B 2 O 3 -SiO 2 glass powder with 1-40 vol% titania powder were investigated. The initially amorphous K 2 O-CaO-SrO-BaO-B 2 O 3 -SiO 2 glass powder formed cristobalite (SiO 2 ) and pseudowollastonite [(Ca, Ba, Sr)SiO 3 ] during firing. The above crystalline phases were completely replaced by a crystalline phase of titanite [(Ca,Sr,Ba)TiSiO 5 ] when the amount of added titania was greater than a critical value, e.g., 10 vol%, at 99-1100 °C. A chemical reaction taking place at the interface between titania and the glass was attributed to the above observation. The dissolved titania changed the composition of the glass, and the dissolution kinetics was much faster than the formation of cristobalite and pseudowollastonite. Activation energy analysis showed that the crystallization of titanite [(Ca,Sr,Ba)TiSiO 5 ] was controlled by a reaction-limiting kinetics of formation for the Ti-O bond.

Redundant coding of simulated tactile key clicks with audio signals

The present study examined the efficacy of using audio cues for redundant coding of tactile key clicks simulated with a piezoelectric actuator. The tactile stimuli consisted of six raised cosine pulses at two levels of frequency and three levels of amplitude. An absolute identification experiment was conducted to measure the information transfers associated with the tactile-audio signal set. Results from Condition 1 (C1) provided a baseline measure by employing only the tactile signals. In Conditions 2–4 (C2–C4), supplemental audio signals were used to encode amplitude cues only, frequency cues only, and both amplitude and frequency cues, respectively. The results showed that partial redundant coding of tactile cues with audio signals could increase information transfer, when the cue (amplitude) was not perfectly identifiable with tactile signals alone (C2). When the cue (frequency) was well perceived through tactile signals alone, audio supplemental cues did not improve performance (C3). With redundant coding of both amplitude and frequency cues (C4), audio signals dominated tactile signals. It was also found that increased information transfer was achieved at the cost of increased response time (C2), suggesting increased mental load associated with the processing of multisensory information. Our findings have implications for the design of simulated key-click signals for mobile devices, and the use of multimodal signals for redundant coding of information in general.

Bandpass Filters With Localized Temperature Compensation Dielectrics in Low-Temperature Cofired Ceramic Packages

A series of SrTiO3 (STO) based temperature compensation dielectrics that were cofireable with the commercial DuPont 951 low-temperature cofireable ceramic (LTCC) were developed. The STO30 dielectric with 30 wt% STO showed the highest positive temperature coefficient of resonant frequency (τf) that was opposite to the τf = -69 ppm/°C of the Dupont 951 LTCC, and was selected to design a temperature-compensated four-pole bandpass filter. The filter shows a near zero τf = 0.7 ppm/°C over a temperature range -20 °C to 80 °C. The variance of insertion loss of the filter over the same temperature span is 0.28 dB. The maximum-difference group delay of the filter is 37 pS. The insertion loss included two SMA connectors at 20 °C is greater than 2.45 dB. A general variational method with the transmission-line technique provided an analytical method to calculate the effective dielectric constant and the characteristic impedance of an arbitrary multilayer strip line structure. With this method, the thickness of STO30 compensation dielectric can be optimized to obtain a nearly full temperature compensation for the filter. The electromagnetic simulation results of the filter agreed well with measured data.