Fig. 3: In vitro testing of Cytophone using vessel phantoms with cell phantoms, ex vivo testing of malaria-infected participant blood, and in vivo detection of iRBCs in infected participants in Cameroon.

a Photograph of the PA probe consisting of an array with 16 transducers and an optical tip, and a simple vessel phantom consisting of a ~1 mm diameter capillary tube with flowing blood. b Linear beam shape at a wavelength of 1064 nm after optical tip before passing through the vessel phantom. c Broadening of the linear laser beam after passing through the vessel phantom filled with blood. d PA signals from pure (left) and contaminated (right) water. e, f PA waveform (e) and PA trace (f) from 0.1 µg/mL synthetic Hz suspension. g, h PA waveform (g) and representative PA trace (h) from an unprocessed blood sample collected from an infected participant. Laser parameters: wavelength, 1064 nm, pulse width, 1.5 ns; pulse rate, 1 kHz; pulse energy, 130 µJ. i, j Typical PA signal waveforms in the dorsum of the hand illustrating before (i) and during (j) the passage of an iRBC through the detection point. k, l Typical PA traces from a malaria-infected participant before (k) and after (l) signal filtration. m Photoacoustic peak rates (peaks/min) from Participant 14 over multiple visits following antimalarial treatment. mm millimeter, arb. units arbitrary units, μs microsecond, s second, PA photoacoustic, min minute, Hz hemozoin, PBS phosphate-buffered saline, iRBC malaria-infected red blood cell. Source data are provided as a Source Data file.