Call for prior art: Can you find better art for this patent that claims novelty based on a comparison of device output with a known constant?

U.S. Patent No. 7,888,125 (Theranos) Filed March 24, 2006 Priority May 9, 2005.

Claim 1 recites:

  1. A method of improving the accuracy of calibrating a fluidic system, comprising:

    a) providing a system for detecting an analyte in a bodily fluid from a subject comprising a fluidic device for providing said bodily fluid, said fluidic device having a calibration assembly and a reader assembly for detecting the presence of said analyte;

    b) measuring one or more parameters that are fitted to a calibration curve associated with said fluidic device;

    c) comparing said one or more parameters with predetermined parameters associated with said fluidic device;

    d) adjusting a signal output from the fluidic device by multiplying a ratio of said predetermined parameters to said one or more parameters, wherein the ratio is selected from the group consisting of: a ratio of maximum signal level during factory calibration to maximum signal level measured within the assay, and a ratio of minimun signal level during factory calibration to minimum signal level measured within an assay.

For this university battle I'll pit Duke and one of their then Ph.D. student's thesis (which results in a company Advanced Liquid Logics bought by Illumina) against Stanford and one of their drop outs (who has a company Theranos).

Can you find better prior art than Duke's:

Amicrofluidic lab-on-a-chip (LoC) platform for in vitro measurement of glucose for clinical diagnostic applications is presented in this paper. The LoC uses a discrete droplet format in contrast to conventional continuous flow microfluidic systems. The droplets act as solution-phase reaction chambers and are manipulated using the electrowetting effect. Glucose is measured using a colorimetric enzyme-kinetic method based on Trinder’s reaction. The color change is detected using an absorbance measurement system consisting of a light emitting diode and a photodiode. The linear range of the assay is 9–100 mg/dl using a sample dilution factor of 2 and 15–300 mg/dl using a sample dilution factor of 3.

The voltage V(t) is directly proportional to the light intensity incident on the photodiode and is related to the absorbance by the following equation: A(t) = ln {(V0 – Vdark) / (V(t) – Vdark)} (5) V0 corresponds to zero absorbance (or 100% transmittance), and Vdark corresponds to the voltage output of the photodiode under dark conditions. The rate of the change of absorbance dA(t)/dt is equivalent to the reaction rate, and is related to the glucose concentration by Eq. (3).

-Srinivasan, et al., Droplet-based microfluidic lab-on-a-chip for glucose detection, Analytica Clinica Acta 507 (2004), 145-50. (equation edited to conform).

  • The interesting stuff with respect to the Duke and Advanced Liquid Logic is the droplet based lab on a chip stuff. As for what I think is described int the Theranos claim 1 step d is really old stuff, like 50+years. Any standard clinical chemistry analyzer does similar things.
    – Eric S
    Commented Mar 30, 2017 at 21:56
  • Interesting historically - During 2013 and 2014 @user3359 posted many questions addressed to issues surrounding Theranos and Elizabeth Holmes. I and others edited many of the questions to remove what looked like personal attacks on her that were embedded in patent questions. Of course I stood up for the integrity of the system and the presumption that everything was on the up and up. Wow
    – George White
    Commented Apr 26, 2019 at 0:41

2 Answers 2


There are about 100 references listed on the patent in question. It seems unlikely that this, or anything, is closer to the patent in question than one of them.

System and method for calibration of a flow device

WO 2006020870 A1

Priority date Aug 13, 2004

ABSTRACT Embodiments of the present invention provide a system (200) and method for rapid calibration of a flow device (30). A flow device can be provided with a calibration flow curve (e.g., represented by an nth degree polynomial) by the manufacturer or a third party. The calibration curve can be adjusted for a process fluid and the system for which the flow device is actually installed using one or more correction factors. The correction factors can be determined for the flow curve based on a simple empirical test or fluid properties of the process fluid. The corrected flow curve is then saved at the flow device so that it can be used for future flow control.

  • I'm not sure the reference you cited though would be considered as prior art. There is a corresponding US application, but ..Publication number WO2006020870 A1 Publication type Application Application number PCT/US2005/028741 Publication date Feb 23, 2006 Filing date Aug 12, 2005 Priority date Aug 13, 2004
    – user3359
    Commented Jan 14, 2014 at 19:47
  • Under 102(e) pre-AIA and under 102(a)2 post-AIA, the priority date from a U.S. provisional can be used to meet a prior art cut off date so the Aug. 13 2004 makes it fair game.
    – George White
    Commented Jan 14, 2014 at 20:23
  • 1
    As long as the provisional was later cited in a published application or granted patent. It is sometimes called "hidden" prior art because it may not be visible at the time of filing.
    – George White
    Commented Jan 14, 2014 at 21:11

The method of calibrating the sensor is not novel. It is the same method used in most systems to calibrate a sensor. Here is a patent that uses this procedure for calibrating fluid flow.

“Electro-pneumatic converter calibration” , Pub # P0859302 A2, Filing Data 1993

Background Of The Invention Electro-pneumatic converters, such as current to pressure transducers are in common use as field instruments mounted in pipeline systems for controlling the process fluid.

CLAIMS(5) 1. A temperature compensation method for an electro-pneumatic converter device (10) having a microprocessor (96) receiving an electrical input signal and other inputs and a current to pressure converter (I/P) coupled to the microprocessor for providing an output pressure signal, comprising the steps of: a calibration sequence including, (1) applying a first temperature to said device (10); (2) applying a predetermined electrical signal input to said device; (3) reading said first temperature and predetermined electrical signal input; (4) determining correction values; (5) storing said correction values for said first temperature and said predetermined signal input; (6) repeating steps (1) and (3) - (5) for other respective temperatures and other respective inputs to store said respective correction values for said other respective temperatures and inputs; a compensation sequence including, (7) reading the present temperature; (8) determining active correction values for each electrical signal input at said present temperature; (9) storing said active correction values for said electrical signal inputs; and an operation sequence, including

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