**5.2. Acoustophoretic manipulation of bioparticles**

Acoustophoretic manipulation of model organism has been demonstrated by Sundvik et al. [39]. They study levitation of zebrafish embryos using acoustic radiation force in a noncontact wall-less platform for a period of less than 2000 s, while the embryos still in development at 2–14 hours postfertilization, and they found that the levitation does not interfere the development, though it might influence mortality rate. Urbansky et al. [40] perform the manipulation of peripheral blood progenitor cells (PBPCs) with the focus on sorting out CD8 lymphocytes (target cells) from the mixture that contains CD4, CD19, CD34, and CD56 lymphocytes as well. They label the CD8 with affinity beads, forming bead-cell complex, to modify the acoustic mobility of the target cells. Furthermore, they modify the medium properties of central buffer, using Ficoll wash buffer, to adjust the acoustic force on different particles, so that bead-CD8 complexes are pushed into central buffer under acoustophoretic force exerted by piezoceramic transducer, while other unbounded cells remain flowing at the side due to lower acoustic mobility. Urbansky et al. [41] further perform separation of mononuclear cells (MNCs) from diluted whole blood using acoustophoretic microfluidic device. They managed to overcome the behavior similarity of MNCs and RBCs in acoustic standing wave by optimizing the buffer conditions to modify the acoustophoretic mobility of the cells. Antfolk et al. [42] accomplish separation of spiked prostate cancer cells (DU145) from whole blood using ACT-DEP-integrated platform consisting of acoustophoretic pre-alignment, separation, and concentration of targeted DU145 cells, prior to single-cell array trapping using DEP microwell. Bacteria manipulation has been accomplished by Ohlsson et al. [38], who developed a microsystem for bacteria separation, enrichment, and detection from blood, as demonstrated in **Figure 3b**. The system is integrated with acoustic separation to remove RBCs from blood sample, with subsequent enrichment of bacteria from plasma by acoustic trapping to polystyrene seed particles, and polymerase chain reaction (PCR) for detection and identification of the bacteria at the final stage. They demonstrate the system using whole blood samples, which, respectively, spiked with *Pseudomonas putida* and *E. coli*. While for virus manipulation, Ness et al. [43] demonstrate extraction and enrichment of MS2 virus from human nasopharyngeal samples by integration of acoustic force to remove host cells, debris, and pollen from the sample and later with electric field force to attract the virus, which is a negatively charged species, and to migrate from sample to co-flowing buffer. Further, Park et al. [44] perform washing and screening of prostate-specific antigen (PSA)-binding aptamer, a single-stranded DNA (ssDNA), using an acoustophoretic separation. The ssDNA pool comprising of ssDNA library is incubated with microbeads which modified with target molecule, before it is introduced to acoustophoretic separation device, where the microbeads with target-bound DNA fragments are focused on central buffer due to acoustophoretic force, while unbound protein and ssDNA are remained in the original buffer at the side flow. The target-bound DNA on the microbeads is collected and amplified by PCR for subsequent round of washing and screening. Recently, Kennedy et al. [45] communicate the process of purifying target biomolecules utilizing acoustic standing wave in a fluidic chamber to partition and maintain solid-phase bead in an acoustically fluidized bed format, for capturing, washing, and elution of target biomolecules, including monoclonal antibody by protein A beads from a crude cell culture system and recombinant green fluorescent protein (GFP) by anion exchange of a crude cell lysate.
