US 12,235,234 B2
Ion sensing device
Hiroyuki Sekine, Kanagawa (JP)
Assigned to TIANMA JAPAN, LTD., Kanagawa (JP)
Filed by TIANMA JAPAN, LTD., Kanagawa (JP)
Filed on Sep. 1, 2023, as Appl. No. 18/241,545.
Application 18/241,545 is a continuation of application No. 17/099,976, filed on Nov. 17, 2020, granted, now 11,846,604.
Claims priority of application No. 2019-236925 (JP), filed on Dec. 26, 2019.
Prior Publication US 2023/0408441 A1, Dec. 21, 2023
Int. Cl. G01N 27/414 (2006.01); H01L 29/786 (2006.01)
CPC G01N 27/414 (2013.01) [H01L 29/78648 (2013.01); H01L 29/7869 (2013.01)] 5 Claims
OG exemplary drawing
 
1. An ion sensing device comprising:
a field-effect transistor including a bottom gate and a top gate;
a reference electrode; and
a driver circuit configured to measure concentration of ions in a sample solution into which the reference electrode and the top gate are immersed,
wherein the driver circuit includes:
a constant current source;
a voltage follower; and
a voltage source,
wherein the constant current source is connected with a drain of the field-effect transistor,
wherein an input of the voltage source is connected with the drain,
wherein a first end of the voltage source is connected with an output of the voltage follower, and a second end opposite of the first end of the voltage source is connected with the bottom gate, and
wherein the driver circuit is configured to:
supply the reference electrode with a constant fixed reference potential; and
output an output potential of the voltage follower.