A flow rate sensor system for measuring the flow rate of a bodily fluid, the system comprising: an encapsulated implant including: a flow tube having an inlet and an outlet configured to receive a flow of a bodily fluid, a heating element externally coupled to the flow tube configured to dissipate heat at a predetermined rate over a predetermined amount of time, a single thermistor 34' externally and directly coupled to the heating element configured to measure a temperature rise of the heating element over the predetermined amount of time, an implant microcontroller coupled to the single thermistor 34' configured to determine the flow rate of the bodily fluid in the flow tube from the measured temperature rise of the heating element over the predetermined amount of time and from a curve fit applied to a stored set of previously obtained calibration measurements, and an implant power and communication subsystem coupled to the implant microcontroller configured to wirelessly receive power and wirelessly transmit and receive data; and an external device including: an external microcontroller, and an external power and communication subsystem coupled to the external microcontroller configured to wirelessly deliver power to the implant power and communication subsystem and transmit and receive data to and from the implant power and communication subsystem. an encapsulated implant including: a flow tube having an inlet and an outlet configured to receive a flow of a bodily fluid, a heating element externally coupled to the flow tube configured to dissipate heat at a predetermined rate over a predetermined amount of time, a single thermistor 34' externally and directly coupled to the heating element configured to measure a temperature rise of the heating element over the predetermined amount of time, an implant microcontroller coupled to the single thermistor 34' configured to determine the flow rate of the bodily fluid in the flow tube from the measured temperature rise of the heating element over the predetermined amount of time and from a curve fit applied to a stored set of previously obtained calibration measurements, and an implant power and communication subsystem coupled to the implant microcontroller configured to wirelessly receive power and wirelessly transmit and receive data; and a flow tube having an inlet and an outlet configured to receive a flow of a bodily fluid, a heating element externally coupled to the flow tube configured to dissipate heat at a predetermined rate over a predetermined amount of time, a single thermistor 34' externally and directly coupled to the heating element configured to measure a temperature rise of the heating element over the predetermined amount of time, an implant microcontroller coupled to the single thermistor 34' configured to determine the flow rate of the bodily fluid in the flow tube from the measured temperature rise of the heating element over the predetermined amount of time and from a curve fit applied to a stored set of previously obtained calibration measurements, and an implant power and communication subsystem coupled to the implant microcontroller configured to wirelessly receive power and wirelessly transmit and receive data; and an external device including: an external microcontroller, and an external power and communication subsystem coupled to the external microcontroller configured to wirelessly deliver power to the implant power and communication subsystem and transmit and receive data to and from the implant power and communication subsystem. an external microcontroller, and an external power and communication subsystem coupled to the external microcontroller configured to wirelessly deliver power to the implant power and communication subsystem and transmit and receive data to and from the implant power and communication subsystem.