Abstract: Surface modifications and improvements to piezoelectric-based sensors, such as QCMs and other piezoelectric devices, that significantly increase the sensitivity and the specificity (selectivity). These modifications can comprise mechanical and chemical changes to the surfaces of the sensors, either individually or together. For example, nanosize structures may be provided on the surface to improve sensitivity. Additionally, chemical coatings may be tethered to the surfaces, walls, or crystal to provide targeted sensitivity. Additionally, porous, layered and multiple sensor arrays may be formed to enhance sensitivity and selectivity.

Abstract: Surface modifications and improvements to piezoelectric-based sensors, such as QCMs and other piezoelectric devices, that significantly increase the sensitivity and the specificity (selectivity). These modifications can comprise mechanical and chemical changes to the surfaces of the sensors, either individually or together. For example, nanosize structures may be provided on the surface to improve sensitivity. Additionally, chemical coatings may be tethered to the surfaces, walls, or crystal to provide targeted sensitivity. Additionally, porous, layered and multiple sensor arrays may be formed to enhance sensitivity and selectivity.

Abstract: Surface modifications and improvements to piezoelectric-based sensors, such as QCMs and other piezoelectric devices, that significantly increase the sensitivity and the specificity (selectivity). These modifications can comprise mechanical and chemical changes to the surfaces of the sensors, either individually or together. For example, nanosize structures may be provided on the surface to improve sensitivity. Additionally, chemical coatings may be tethered to the surfaces, walls, or crystal to provide targeted sensitivity. Additionally, porous, layered and multiple sensor arrays may be formed to enhance sensitivity and selectivity.

Abstract: Surface modifications and improvements to piezoelectric-based sensors, such as QCMs and other piezoelectric devices, that significantly increase the sensitivity and the specificity (selectivity). These modifications can comprise mechanical and chemical changes to the surfaces of the sensors, either individually or together. For example, nanosize structures may be provided on the surface to improve sensitivity. Additionally, chemical coatings may be tethered to the surfaces, walls, or crystal to provide targeted sensitivity. Additionally, porous, layered and multiple senor arrays may be formed to enhance sensitivity and selectivity.

Abstract: There is set forth herein a sensor for sensing of substances. The sensor can include a sensing crystal oscillator and a reference crystal oscillator. The sensing crystal oscillator and the reference crystal oscillator can be arranged in a phase locked loop so that the oscillators oscillate at a common frequency. The sensor can be configured so that there is a baseline phase differential between the oscillation frequencies of the sensing crystal oscillator and the reference crystal oscillator. Detectable substances accumulating on the sensing crystal oscillator will induce a phase shift between output frequencies of the reference oscillator and the sensing crystal oscillator to allow for highly sensitive sensing of substances in small concentrations.

Abstract: There is set forth herein a sensor for sensing of substances. The sensor can include a sensing crystal oscillator and a reference crystal oscillator. The sensing crystal oscillator and the reference crystal oscillator can be arranged in a phase locked loop so that the oscillators oscillate at a common frequency. The sensor can be configured so that there is a baseline phase differential between the oscillation frequencies of the sensing crystal oscillator and the reference crystal oscillator. Detectable substances accumulating on the sensing crystal oscillator will induce a phase shift between output frequencies of the reference oscillator and the sensing crystal oscillator to allow for highly sensitive sensing of substances in small concentrations.

Abstract: A molecular spectrometer is provided that performs Fourier analysis utilizing the discrete Fourier Transform on a digitized time domain waveform that relates to the composition of a sample. Digitized reference waveforms are employed to permit the instrument to limit its analysis to frequencies of interest and thereby increase the rapidity of the analysis. Data at differing frequencies can be resolved at independent resolutions, and the instrument can analyze spectroscopic data in real time.

Abstract: This invention relates to the use of a series of Discrete Fourier Transform (DFT) operations to provide multi-dimensional analysis of a molecular specimen.

Abstract: An RF control system suitable for use in a mass spectrometer of the type having an ionization chamber, a mass filter and an ion detector. A constant frequency RF voltage is applied to the filter. The magnitude of the RF signal is varied in response to a DC control signal to permit selected ions having a desired charge-to-mass ratio to pass through the filter and strike the detector. In the control system the generated RF signal is attenuated and added to the DC control signal. The resultant voltage is applied to a comparator-integrator circuit that is arranged to provide a control signal capable of precisely holding the output of the RF generator at a predetermined peak voltage.

Abstract: A leak standard generator which utilizes the diffusion properties of a gas or vapor to deliver a uniform rate of flow of a leak sample into a diluent gas stream. The generator includes a reservoir containing the leak sample, a discharge head through which is passed a metered flow of diluent gas and a diffusion tube of prescribed dimensions for carrying a gas or vapor of the sample from the reservoir into the diluent gas stream moving through the discharge head. Heating means are provided to maintain the reservoir and the diffusion tube at different temperature levels to promote uniform movement of the sample gas or vapor into the diluent stream.

Abstract: The invention relates to an arithmetic unit fabricated by large scale integration techniques and to an improved digital network of increased accuracy in which the unit finds application. The integrated circuit comprises an initial summing means, rounding means, full precision multiplication logic and three successive summing means, all elements being successively connected, and all except the first having both internal and external input terminals. The unit is flexible in respect to the length of the operands and their sign notation. The terminals are readily cascaded, permitting interconnection of the unit with like integrated circuit units and with external delay elements. The invention is applicable in a variety of complex operations including digital filtering, correlation, convolution, polynomial evaluation and squaring. In many of these applications, mixed precision and rounding provide increased accuracy in the resulting digital networks.

Abstract: The invention relates to a recursive numerical processor for data in word serial form in which bias errors are reduced by use of a property of two's complement notation. The input data is introduced in two's complement notation. The processor includes a sub-processor, typically a multiplier, introducing a bias error on the order of the least significant bit. The bias error arises from truncation or rounding necessary to avoid word growth in the processor. In accordance with the invention, the sub-processor is provided with a sign inverter at its input and at its output and the two sign inverters perform a double sign inversion on alternate words. Alternate word sign switching causes the error to alternate between being too large and too small (in magnitude), a property of two's complement notation, thus cancelling a very substantial part of the bias error. The invention has application to a number of recursive numerical processors including recursive digital filters.