High balance gradiometer

A method for constructing a gradiometer with high balance, said method comprising the steps of:

• (i) winding a continuous wire onto two or more substantially horizontal and vertical grooves on a non-magnetic non-conducting support, both said wire and support having either equal, or substantially equal, coefficients of thermal expansion, said wire wound under tension on said substantially horizontal grooves forming gradiometer coils and said wire twisted and held in said vertical grooves forming a twisted pair, said twisted pair connecting said gradiometer coils;
• (ii) applying a glue in the process of winding of said wire to hold said wire under tension in said substantially horizontal and vertical grooves.

A gradiometer support system operatively connected to one or more SQUID channels used in measuring magnetic fields associated with a heart, said measurement based upon the amount of current induced in one or more gradiometer coils in said support, said support system further comprising

• a non-magnetic non-conducting gradiometer support having a first coefficient of thermal expansion, α1, said support further comprising near horizontal grooves and vertical grooves, and
• a continuous wire with two or more gradiometer coil loops connected via one or more vertical twisted pairs, said loops of equal area and said wire having a second coefficient of thermal expansion, α2, said α2 either equal to, or substantially equal to, α1, and said gradiometer coil loops residing under tension in said near horizontal grooves and said vertical twisted pairs residing under tension in said vertical grooves, said wire being wound under tension and held in place on said gradiometer support using a glue.

A cardiac device for measuring magnetic fields associated with a heart, said system comprising

• a gradiometer support made of Pyrex comprising near horizontal grooves and vertical grooves;
• a continuous Niobium or Niobium alloy wire with two or more gradiometer coil loops connected via a vertical twisted pair, said loops of equal area and said Niobium wire having a coefficient of thermal expansion either equal to, or substantially equal to, that of Pyrex, and said gradiometer coil loops residing under tension in said near horizontal grooves and said vertical twisted pair being wound and residing under tension in said vertical grooves, said Niobium wire being wound under tension and held in place on said gradiometer support using an cyanoacrylate glue, and
• at least three optimized SQUID magnetometers aligned in the X, Y, and Z axes measuring magnetic fields along said axes, said magnetometer outputs, when inverted, essentially canceling gradiometer imbalances in said X, Y, Z directions.

A cardiac device for measuring magnetic fields associated with a heart, said system comprising:

• a gradiometer support made of Pyrex comprising near horizontal grooves and vertical grooves;
• a continuous Niobium or Niobium alloy wire with two or more gradiometer coil loops connected via vertical twisted pairs, said loops of equal area and said Niobium or Niobium alloy wire having a coefficient of thermal expansion either equal to, or substantially equal to, that of Pyrex, and said gradiometer coil loops residing under tension in said near horizontal grooves and said vertical twisted pairs being wound and residing under tension in said vertical grooves, said Niobium or Niobium alloy wire held in place on said gradiometer support using an cyanoacrylate glue, and
• at least three optimized magnetometers aligned in the X, Y, and Z axes measuring magnetic fields along said axes and compensating gradiometer's mechanical imbalances in each of said axes with coefficients close to unity.